Well using heat tape on the side or top is doable. A lot of guys use heat tape on the side for neonate GTP tubs.
As for ambient temps, 77F isnt bad but I wouldnt want it to drop from there. Like i said, i keep the cage temps on all my snakes anywhere from 77-80F and they spend most of the time on the cool side anyways. But like i said, I wouldnt want it to drop lower.
You could poach the T8 from Geoffrey's and put him in a tub with heat tape on the floor of the cage. But again, i wouldnt want it to get below 77F although he could handle a drop much better than a baby boa.
Time to order another T8 for Geoffrey lol.
And i personally wouldnt worry too much about the traffic. Boas are kind of like retics, they arent really too scared. just give him a couple appropriate hides and he should be fine.
For feeding with Gina, i fed her every week when she was on small hoppers and as the mouse size increased, so did the time frame. By the time she was on adult mice, she was eating every 14 days. And now that she is on weaned rats, she gets those every 2 weeks as well.
You will know when they get hungry as they will be out at night creeping around lol. i catch Louie and Gina out creeping around on the plants and shelf or sitting on the litter dam when it gets close to dinner day. Same with Luna who is supposed to be an ambush predator lol.