OP has a first Gen (05) which does not have as much overhead as 2nd Gens or later. The higher output stators for first Gens only make it similar to the output power of your stock 3rd Gen. Also worth mentioning that people seem to have more trouble with the higher output stators burning up than the OEM ones.
Best bet for first Gens is to get a dash mounted voltmeter and keep an eye on the regulator voltage at the battery terminals. When it starts dropping much below 12.8V running down the road you know you are drawing too much current to your accessories.
On my old 1st Gen, I used to be able to run 2 heattroller modulated, 90W jacket liners and two pairs of heated gloves, along with a set of LED aux lights and everything was OK. But turning on the heated grips or running halogen lights (before I got the LEDs) would draw too much. Now on my 3rd Gen I run all that stuff and more and dont even have a voltmeter.
To the OP, splices done correctly shouldnt be a problem. Make sure that you use correctly sized butt splices that have weatherproof heat-shrink insulation, and do a good job crimping them. You can also use uninsulated Butt splices, solder them in, and use weatherproof heat shrink tubing with the hot melt glue inside.