I guess, since whistles are suspect, the only thing a motorider can do is try to lower the odds of having an unexpected conference with a piece of venison. I live in a heavily forested area and it's just scary as hell, especially at night, riding out where there is any kind of cover for the little bastards.
Even though there are collisions during daylight, as what happened here, most deer are down during the daytime. That said, I've been extremely lucky in that I have thousands of nighttime miles logged and have yet to have even a close encounter with a deer. I just hope it isn't one of those inevitable deals, mathematically speaking.
At any rate, I'm happy that you and the better half are in good shape. Reading these stories always gives me pause to think a little bit about the dangers out there on the highways an byways.