I believe isuzu don't recommend towing with the VX because of the TOD system.

To me 5000 lbs is way too much for the VX that weights 3998 lbs,which means you're about to tow 35% more then VX's gross weight.

Why don't you rent a dodge ram,F-250,toyota tundra or similar truck & save your self a headache & the rig from being damage ?

Personally i wouldn't do that sort of towing,just my opinion