I rented a trailer last year to pull a tractor with 18.4-38 tires on it. The dealer pumped up the tires about 15 pounds over normal, & I squeezed the tires between the fender wells touching on both sides, & hauled it 100 miles. The trailer was 14,000 GVWR, & the tractor I was told had no fluid in the tires. Wrong! Found out later there was 2200 lbs. It put me 1 ton overweight. If I didnt take off the front weights it would have been another 800lbs on top of that. I have also looked at PJ trailers; but I will have a deckover bumper type so I dont have to mess up the pickup bed!
The drive over fenders wont give You a descent 60 - 40 load which is the proper trailer balance; unless You drive the rear tires partially between the fenders on most trctors. You dont want to chain a tractor down with them on the fenders for sure.