"Reptiles, Amphibian, and Cat. Oh my!"
Howdy from Grimes County neighbors, and welcome to the asylum!
I've a pile of chit to do before the heat really comes on, but after reading your post, I'm intrigued. Enough so that my head'd implode if I left it unaddressed.
Hope it works out to be mutually beneficial, but if I were you, I wouldn't count my tortoises until they hatch...
Insulation, and LOTS of it, with reliable climate control are critical to your critters' health and survival in a Skoolie.
At it's most basic, a bus is a mobile greenhouse. Interior temps rapidly
outstrip ambient temperature. Think the heat indexes are bad here? You ain't seen nothin'
The turtles are best suited to contend with higher temps (within reason), the others will wilt pretty fast. Cold climates will present different challenges, so lets Tupperware that issue, and huck it into the fridge.
Reflective covers over all that glass is of a considerable help, but you'll still need to learn how to keep the temperatures within an acceptable range.
By the sound of it, I presume all y'all are looking to full-time it. Access to shore power will simplify the problem considerably.
If you intend to boondock, wa'al... That can be several orders of magnitude more difficult to acheive; unless you find yourselves tiring of mock
turtle soup & faux frog's legs. (I'd also address the gato, but this is a family-friendly forum...)
You will need to delve deeply and peruse assiduously this awesome forum for the threads that will guide you in all
aspects of your conversion, most notably A/C, and methods of insulating the ceiling and floor.
And never forget that rust doesn't sleep, and that cold descends...