You won't need to, and shouldn't, use your rig to drive around and sightsee. There are frequent free shuttle buses to all the major Valley points of interest. If you want, you can also take an open-air narrated tram tour (about $20/person) to the west part of the Valley. If it's a light snow year, the bus to Glacier Point may be available.
Even though you might "miss the comforts of home" when you aren't with your rig, using the shuttle bus is the right thing to do. They're non-polluting (the Valley is an enclosed space on three sides, so smog tends to accumulate) and using them reduces congestion (which can be insane on a busy summer day or a weekend). Also, the shuttles will take you to several points of interest in the eastern part of the Valley that are closed to cars altogether. Much better to ride the shuttle in comfort than to wrestle your rig through traffic and try to park it. And did I mention--the shuttle is free!!