Don't forget the dwarf Boa's as well, like Hogg Island Boa, Sonorans, Crawl Cay's, Caulkers Cay's and Pearl Island and Nicaraguan to name a few.... These only top out at 4-5ft at the most (depending on sex) but still have the wonderful character of larger Boa's.
Excellent suggestion. .. here's my Dwarf SunGlow Boa ..he's over two years old and I don't think he's reached 30" yet !