I known you have a lot of time and $ invested in your vehicle. A thought on a good platform that would meet most of your needs and have a quick resale at a good price if needed. Some or all of what you might think about in in search of a trail.
Legal trailer over all width would be 102", two 8" wide finders would give you 84" between. As trailers go, a 96" over all trailer deck and finder width, are easier to pull and keep between the lane lines (Truckers ruts). Reinforcing diamond plate finders can make it strong enough to hold the weight of your heep driving over them. Or you can stack 2x6 lumber on the inside of the finders to form a ramp/bridge, assuming 8" tires or more on your 90" wide monster. Also, an 18' bed plus 3' tong (21' over all) makes for a good pulling length with dual axles set back a little. (It can hold a 1960s full size car when thinking of resale.) I believe trailer safety will be targeted soon, so brakes on both axles, a brake away kit and over all weight of the above could include your trailer spare, 4 extra tires, a tool chest, ramps, a dirt bike, est.
Don't use car/truck tire on double axles. (Or any trailer for that mater.) They can't take the scrubbing force in turning. I run my 10 ply trailer tires at 50 psi. for good ware. I don't carry any of the above except a spare add on, just my 2 ton XJ. My axles and springs are 3500# each.
I got carried away I guess.
That welder sure sounds like a good price. It should sale quick.