Sena powers by USB. Phone powers by USB. Power bank powers by USB. Some nights you will be at a hotel, so easy to charge your various items on 110V in the room.
You can do a fairly clean SAE panel mount to each side case and/or the top case, IF you want that. (Top case may simplify things) You'll just have to remember to un-plug prior to removing the side cases. Shouldn't be a big deal on a day to day basis, though some members do just pull the entire side case off to take into the hotel room. I always used a liner bag and left the hard case on the bike. SAE to USB on the inside is simple enough. Lots of options, should you go that way.
Power bank Vs 12v power on the bike; 12v power is always there. Power banks just add another item that needs to be charged. Depending on the size of the power bank, you might not need to charge it every day for Sena use.
The Sena lasts ~6-8 hours. As previously said, if you plug them in at lunch to charge while you're eating/stopped, you can just about get all day. Some days you may require more. You can panel mount a USB port or even a double USB port at the back of the FJR pretty easily. And just as easily panel or bar mount one up front. Realistically, you won't need to charge the Sena all that much. And if you do need to, you're going to stop and plug in. It's not realistic/safe for the rider to pull out a cord and plug into the Sena. Your pillion might be able to do this for you, but likely not too easily for herself. That port can be hard to find with gloves on, going on feel alone. I do know some riders that say they can do it though.
Spotify - Great. Nice option.
Sena running music and comm should still last ~6-8 hours. Varies daily. Yes, you could plug in the power bank at the start of every day, but you really don't need it for hours so it seems silly to do so instead of plugging it in when you actually need it. Stops are good when you're in tourist mode. The power banks do have the benefit of not being connected to the bike.
With a wired connection to the Sena you are charging the Sena batteries faster than you are using them. So plug in a couple hours before you get to your daily destination and you'll be fully charged when you get there. One less thing to worry about for the next day. If you simply make that a part of your routine, plugging in the Sena for the last segment of your day's ride, then you'll always have fully charged Sena units at the end of the day.
GPS. Never, ever, EVER charge your GPS like it's a stand alone device. You're wasting your time and everyone else's patience. There is no reason to not have the GPS hardwired on the bike.
Tank bag - You kids!
Something you can do to simplify gas stops. Remove the flap/spring on the gas cap. Cut down a key and install a small knob from the hardware store on it so that it fits flush into the gas cap. This is subtle and makes your existing cap easy open w/o removing the ignition key. The key is too short to use to start the bike. (It might work in the bags, I don't recall) You can buy a replacement rain cover. It's not really that big a deal, is it?
Strap style bag, un-clip at the seat end and just flip it up.
Magnetic style bag, lift up and set to the side on the tank.
Ring mounted style, (my personal preference)- pop off and set up on the bars.
I'm already pumping gas and you're still playing with your key. I don't see the problem.
Put tank bag back in place, remove fuel log from tank bag and fill it out from the receipt, (for Cert ride or rally w/fuel log). I don't get off the bike or even take off a glove at gas stops. Now, in tourist mode, none of this matters.
Powering the tank bag means a shorter electrical run, easier access to any item you are charging inside and gives you options like plugging into the inside connection and running the cord to the Sena if you have an issue with the other power port you normally use or a power bank goes flat.
Phone use: Consider how you use your phone and how often you need to access it during an average riding day. Do you NEED it powered up all day? (edit - Sorry, forgot you are pulling music off the phone, so yes, powered all day.)
Or are you only accessing it during stops? I don't know your needs or use habits. I know plenty of riders that make more calls than I would have imagined while riding.
For me, I'm RIDING. My helmet is not a phone booth and I've got more important things to pay attention to than the phone. If you need the phone on all day, keeping it plugged in means it's always fully charged. Or keep a power bank just in case you need more phone battery, rather than having everything plugged into power banks.
Go for some rides. Keep track of how much time you're actually riding on a 12 hour day. Turn the Sena off when you're not on the bike unless it's a short stop. A relaxed 12 hour day for me is about 600 miles. That's with gas stops, photo stops, potty stops and a nice lunch break. Having spent the last 8 years riding with my wife, (she rides her own bike), we've done ~170k miles in that time. We've ridden 1k days together, but in touring mode we slow the pace down significantly. We were doing 200-400 mile days on our 8k mile, 30 day Alaska trip. More recently we often only ride 200-300 miles because we're stopping and enjoying things along the way. Exploring side roads, etc. This doesn't necessarily mean less Sena time, per se, but my point is that you may discover that 12 hour riding days is unrealistic for maintaining a happy riding partner. Especially if your sleep quality is less than stellar. Not to mention the required time to set up and tear down camp.
I'm also an IBA member.
We have quite a few here and a tremendous amount of knowledge and experience among the forum members.
Eric V #488