done it before
I own a retired 2002 wheeled coach type I that I use to tow. It can be done but it ain't easy.
most modular units have a 2ft frame extention butt welded onto the existing frame it is not too strong. On mine I mounted a regular hitch onto the stock frame and used a 16" extention, it works for my boat but not for much else.
However mine is a classV 2x2 reciever, i've been told that if you were to use a classV 2.5" x2.5" hitch with an extender it would take more weight. Not sure how heavy your trailer is. I actually worked for ford for 3 years on diesels and can tell you that you would be better off using a f-series chassis,
7.3 vans do not have innercoolers and 6.0l vans use smaller ones and have less boost and hence less power, also the 7.3l 4r100 transmission usually has a hard time in ambulances that do not tow. I would recomend a f-450,or f-550 ,7.3l s are a lot more reliable than 6.0s however the new 6.4s are wonderfull to drive and will tow almost anything they are just freaking expensive. There are companies that make"bulletproof" 4r100s that work pretty darned well even with"chiped" trucks.
The only problem I had was the electrical, believe it or not even ambulance prep package vehicles come with the same trailer brake and trailer lighting equipment as pickups. However if your rig has amber turn signals you will have to use a euro taillight converter. You would have to hookup the converter, then put some sort of restistance (I used marker lights) in parallel with the converter input (velicle harness output) to make the converter work. hope this was helpful.
