Glossary-
AWD all wheel drive
4WD four wheel drive
2WD two wheel drive
FWD front wheel drive
RWD rear wheel drive
Jack-
I don't know that it's a transmission problem (it may be, for all I
know about it -- A LOT depends on the particular vehicle and its
ratings) as much as it is a loading problem. Packed for travel,
there tends to be a lot of stuf loaded in the back of anything. Then
you add in the tongue
weight at 10-12% of the trailer's loaded
weight. All this tends to "seesaw" the truck/van, putting more
weight on rear
axle and less weight on front.
In RWD, this leads to increased traction, but less
positive "tracking" of steering and odd angles on the frontend
alignment (which is usually done with the "normal" load on the
truck/van).
On FWD, you not only have the tracking and frontend problems, you now
have a potential traction problem.
The answer is a weight distributing hitch (WDH), which forms an
adjustable "bridge" between the truck and trailer, spreading some of
the rear
axle weight to the front
axle and trailer axle, which has
the effect of putting the front wheels back down on the ground where
they belong.
A side note: Altho I have never pulled a trailer of much size with a
FWD, I have owned three (a French Citroen 2CV6, an East German Trabbi and an Amurrikin Saturn--total HP between ALL of them was only 137!), and you certainly tend to have great traction under normal circumstances because the heavy end of the vehicle is over the traction wheels, plus I noticed in general that the back wheels are more likely than the front to be on slippery stuf. The same traction reasoning applies to the other end with things like VW dune buggies.
Pete and Rats