box truck to toy hauler conversion

Funny you mention this. On a road trip now and on the way down I passed several rigs like this on I-5. Hadn't ever seen one before. My first thought was "I wonder if those companies sell those cheap when they are done?". For recreational use you would never wear one of those out and servicing one at any big truck shop would be easy.

 

I saw a double-decker bus this morning. The back section in the upper level was open. I thought that would make for a very good race hauler/race watch platform.

 

Just google expeditor trucks for sale and you will see a variety rigs at various price points and condition. They are built to cover more miles in a week than most of us will see over a race season.
They are /were commercial vehicles so you would need to know the laws in your state to convert it to a RV and get it titled correctly.