Then that might be an excellent option for you. I'd do a search here for reptile room, or room builds and see what others have done in the past. I *think* OWAL had a thread showing a progression on a build he was doing, but I can't remember if it was a reptile or rodent room.
Two big considerations would be electrical... You'd probably want that "room" on its own breaker and to have a very good power supply available and a lot of outlets in different places. Also, plumbing... It is most convenient to have a large wash sink (utility sink) to clean tubs in. If that won't work in the space you have for the room, you might want to consider having one in the garage right outside the room itself.
Good luck with your project!