it can be done, in fact just about anything can be done within reason and game capabilities. a few of my buddies that build mods do just that. mix-match different vehicles parts to do a more "modified/custom style" build.
now of the not so good part. not all, but most builders i know make stuff for themselves and once they feel it is done or they have gotten tired of it and moved to other projects is when they tend to release things. they do not do request or at the very least it is very rare they do. however there are still plenty of people out there who are willing to do build requests, so do not get your hopes down. it may take a little bit before you find someone though.
sounds like a cool rig, maybe post a pic or two of it. that might be enough to inspire someone to consider it more. i have had friends do this, not interested in a build someone suggested, only to then see a pic of the said vehicle or a different style of build for that vehicle to get them motivated on the project.
best of luck with your project