Well nobody said making, converting and importing models into a game which was never intended to be moddable would be easy! Try making something from scratch and THEN you'll understand the pain of Trespasser modelling...For the selecting each object to import thing... uh way too much work.
At any rate, Shep, I started going all the way through the JPOG models and converting them to Tres format, fixing them up and splitting them into separate meshes along the way. I did the Balloon Tour you were having problems with (can understand why now - it took me an hour and a half to fix just the main building), as well as some trees, misc objects, the two dino feeders, and the fountain (which has real Tres water now). Stopped on the Hatchery because I suspect it to take the longest of anything, but I will start on it tomorrow.