well kevin, i suppose the maximum sane height would depend on how you raise it, what materials are used, and of course what, if anything do you plan to mount closer to the roofline or put into upper your cabinets. My godfather built a bus similar to the "azalea" bus, but his was framed like a house, very heavy too. His bus was about the same as my dad's (now the azalea bus) which is 12.5". he would always make comments about how if he ever had his tip, all he would have to do is get it back on all four and fix the siding. well, a cloverleaf in near the bronx proved him wrong some years ago. his bus was, we put it, "toothpicks". I can also say that my dad's (once again 12.5" tall) was built with cedar, redwood, & aluminum wall studs. i know it's not exactly sturdy material for a bus, but it easily holds up to everything unless it rolls over. as far as being top heavy, unless someone was sleeping one of the lofts it was amazingly lightweight. you wouldn't believe how far i've seen it tilt to one side then just come right back up. anyways, point of the story is that height is not as much of an issue as top-heaviness. anyone care to perform some not-so scientific tests to find our "sweet spot" for raised roofs? lol!