Jo, I was thinking matching the RV to the VX, but then it would look like a space shuttle.
The diesel pusher RV gets about 9 mpg towing the VX and I have gotten 12mpg on flat ground without towing. The RV weighs 30,000lbs and hauls about 6,000lbs with the trailer and VX. On a pound per mileage basis the RV wins, but it hurts like hell to fill the tank($400).
The VX has receiver hitches front and rear for my winch and ball hitches. The trailer has a hitch on the front(naturally) and I put one on the rear. That way I can put the ball hitch on the front of the VX hook it up to the back of the trailer and push the trailer in a parking space. This allows me to use the winch on the trailer to pull the VX on the trailer so I only use one parking space like in my garage. I always try to get pull throughs at campgrounds, but sometimes that doesn't work out, so I use the VX to maneuver the trailer.
We just took a five week trip from Florida to PA and everything worked just fine. The combination of RV and VX works. I even used the trailer when I had crawl under the VX to adjust the shift linkage after a particularly rough dirt trail.
We hope to do trip out west next spring starting with the Moab meet.
Mike