I am thinking that your choice of a fifth wheel might not be the best choice. If you were able to live in a small enough travel trailer that could be pulled by an Excursion, you would have a good vehicle to keep your musical equipment in.
Now if you are able to transport your equipment within a secure vehicle, it is much more secure than in almost anything else, and capable of being parked with alarms.
County fairs, swap meets, beer garden events where athletic people like to dance the evenings away might fit the bill and earn you some scratch, but as others said, workcamping in a campground to earn your accomodation might be a good way of having a home.
Getting to really be able to know what is good and what is not good, or having capable friends that know the ins and outs of buying a used unit is worth your weight in gold.