Ok -I'll jump in on this since my name is being dragged about
I had to build one of these as the LWB M48 2.5 ton tractors are near impossible to find, and the M275s just seemed too short.
The tractor we built up does very well. As Kenny mentioned, I opted for the 5 ton setup as it is much heavier duty than the 2.5 ton ones - including the L/R rocking mechanism. It also gives you just a bit more height over the 2.5 ton one and makes the trailers set a bit more level. I like the approach a lot better on these as well.
I went with the pipeline truck/winch setup on the rear and then we mounted the fifth wheel as close as possible to just forward of the duals. It could have probably gone forward another inch or two to be perfect, but we didn't have room for turning on the trailers.
The way we did it, I can't haul all the military trailers out there - for example, I have pulled a military 40' data center van with it, but the front air conditioning brackets had to be pulled. It would just clear on the level, but offroad while turning there wasn't enough room.
I have one of the expandible van trailers - you can see it in the last picture of mine, and we removed the box off if it. Getting ready to add a dovetail frame section and then building a flatbed out of it for transport.
5 ton approach with bobbed frame, 5 ton fifth wheel, 2.5 ton tractor crossbar and fenders, and then the pipeine setup. 5 ton tool box was shortened and rotated 90 deg. and then the joystick placed on top of that.
We tapped into the wiring and air lines so there is still all of that on the rear, as well as by the joystick.
Also had enough room in front of the fenders to add some brackets to store a military tow bar across the back for flat towing operations.
I just used it a couple months ago to flat tow a 27,000+ lb military crane from Northern Ohio down to the farm in SE Ohio. Was SLOW on all the hills, but pulled it well. The data center van I used to pull with it weighed in at probably about 25-26ooo lbs and it seemed to do pretty well.
Mine gets used every now and again - about as much on-road as off-road. In the process of changing everything over to 12.5x20 XLs and keeping the tandem duals (haven't figured out the dual spacing issue yet with these but working on some ideas) to give it a bit better wet weather traction. Will probably be adding air assist steering here soon as well as with the front winch on it, it is a bear to maneuver into tight spots.
If you are thinking about it - go for it. I love mine and tend to use it more than some of the other trucks. They work well!