Not sure what I should do...

Put the 75-qt tank up on wooden blocks or books so it's not sitting directly on the floor.

If your camper gets cold again - likely in January - put each of the snakes into their own pillow case and put them down your shirt. At night you can put the pillowcases into a plastic tub and put the tub under your bed covers to keep it warm. The tub is in case one pees it won't wet your bed.

Can you borrow a space heater to get the ambient temp in the camper higher? If you can keep it around 84*F you won't need supplemental heat or lights.

Well, we have 2 small space heaters pointed at their tank now, where as we only had one before, also now with the lights and heating mat. We did cut back one heater though last night, but still had night lamp on. It's right around 85 in there now. But thank you on the advice about setting it on blocks. Not sure why it didn't occur to me before, but it did not. We also found some piece of foam we could cover one end of screen lid to up the humidity Saturday night so that has improved as well...Though I still am not sure of where the ideal humidity level is...I get too many answers that vary too widely. And once our temps outside drop again, for Im sure they will, before we either get into a home, or more housing, we shall use the pillow cases and keep them warm. Thank you for that advice.

Ideal humidity is 50-60%... You can use damp heated towels over the top of the area your heat lamp isn't, soak the substrate if using cypress mulch, sphagnum moss, etc. Or a larger water bowl near the heat source also helps. Excited that y'all are making progress. We are here to help so no question is a stupid question when it comes to health and safety.

We have successfully reached ideal humidity then! We have some type of mulch I think as well as moss, which we just switched to I may add.

Make sure there is no pine or cedar in that mulch.

I do not believe there is, we bought it from Petco. It's called forest floor bedding, 100% Cypress mulch.

Yikes. This is why pets make terrible gifts. Could you ask your family where they got the snakes and see about returning the remaining one? I feel like that would be best for the snake and your sake.

I'm not sure what you mean by "returning the remaining one." We have 3 of them now...And all are still alive. And I'm not sure as to how returning it would be best for my sake...I need to learn to take care of them...Which, from my understanding, is what this site is for...

as I'm new to this particular forum I'll keep my comments mostly to myself other than you take WAY too much offense to people...on the internet...on an open forum. There was plenty of advice to help your keep your 3 bps in way less than optimal conditions.
The point a lot of these people are making is its not about learning if you don't have the means to provide completely proper husbandry to your herps or any animal for that matter. I'm just being factual, not trying to beat you down, but if the issue persists or other issues arise then it is absolutely in your best interests to rehome those animals until youre ready to take care of them again. That's just my .02

Thanks for your.02 lol. We are getting all the things we need to properly house them. And minimize stress, as well as new home for us. The whole purpose to this was to make sure the one that over ate would be OK, and signs I should watch for that he was in fact not OK. We never had any intentions on leaving all 3 in one tank, just until we could get housing for all. And if things arose that we couldn't take care of them we in fact would, and will rehome them. But we just want to make sure we are doing things as properly as we can. But we just have to know all things we can, that's all. But I thank you for your concern and everyone else's concern for these beautiful creatures.