By the time you stretched that frame out far enough to add a ramp body to the back of that 4 full size door cab, its going to be really long. Would be a real pain to drive around my town, couldn't make most of the turns without backing up a few times. Gene

I've had and used four ramp trucks to race with, #2 was a 1955 Dodge D500 17 ft. flat bed that I had my Father in Law make a ramp truck out of it, I ended up replacing the original 264 C.I. flat head six cylinder with a 1957 392 hemi motor out of a New Yorker I had wrecked and save. The truck came with a 4 speed truck tranny and a two speed vacuum operated rear end, I converted the truck to 12V when I swap the motor and I ended up running either 900x20 or 9.50x20 inch truck tires, it came with 8.25x20 tires originally. the taller tires help it go down the freeways in CA a lot better with the 392 motor
The first ramp truck I drove and used to help a race partner was theirs a 1968 D600 318-3 engine with a 5 speed tranny and two speed rear end, it was nice.
The next one was a 1973 Ford crew cab one ton single wheel pickup that I had five feet added to the frame and had the same company put a 12 Ft. flat bed on it, I wanted them to put a either 14 or 16 Ft. flat bed on it but they wouldn't so I had my father in Law add a 30 inch long adjustable dove tail to help load my cars on it better.
That truck had a 390 two barrel motor with single exhaust, I added a four barrel intake and 4 barrel carb and had a dual exhaust system install on it, it had 4.10 gears in the Dana 70 and that truck rode, stop and perform very well
The last ramp truck I had was bought was to fill in temporary when I sold the Ford for way more than I could turn down for it It was a 1957 Dodge one ton dual wheel truck that had been converted to use as a roundy rounder racers truck hauler, it was flat wore out when I bought it
I ended up keeping it for several years and I had to replace the motor, cab, reline the brakes and replace the rear end to make it safe to use.
I bought a used 26 ft. class A motor home and a 24 Ft enclosed car trailer and have used enclosed car trailer since 1994 or so
I've thought about buying a longer goose neck trailer with living quarter in it but I probably won't as I don't race that much anymore, especially out of town

I built mine in 1986. I did the 4 foot stretch with a 6 inch angle underneath both splices that extended about 2 ft past. Bed was 18 by 8. 14 ft of flat and a 4 foot dovetail. It was a 74 440 one ton. I only used bump stops on the rears. It did everything I wanted it to do. Birdtracker