I seriously doubt solar panels would generate a meaningful amount of range. You have to remember, that if you put solar panels on, now you just increased the weight of an already heavy vehicle. Solar panels on top of a trailer would also only generate 100% capacity at noon in the middle of summer near the equator. Any other time they would generate a significant amount less. Now you also have to clean the panels regularly and they have to be replaced as they wear out or break.

Solar panels on moving vehicles is just silly. Absolutely not worth it on anything other than a bicycle to charge your phone.