If I were in your position, I'd get the motorhome. Get a diesel pusher - better resale I hear. You can keep your stuff cool in there by using the coach's AC or a cooler. You can get coolers that plug in to a 12v power outlet, or you can put stuff in the fridge. It all depends on what temp you need to maintain and volume. Tow your Range Rover and put the display stuff in there. Get magnetic signs for advertising that you can put on or take off - lots of people do this. You have a website I hope...
Only you can determine if you need to park the coach offsite and drive the toad to the show. Just depends on location and your level of comfort which will insrease as time goes on.
If you have specific questions regarding a class A - maintenance costs, brands, etc, there is a forum on here for those. Ask if anyone tows a Range Rover or writing off business expenses for instance.
Sounds like an awesome way to make a living to me!
