There is very little room available at the 4 lane ramp. What looks like room to the novice is actually the backing and turning space needed to get mutli trailer rigs on and off the ramp. One car parked in the wrong spot and no one can enter or leave the ramp.
There is no parking allowed at the ramp (OK, there is one handicap space near the toilets, but you can't use it), you are expected to wait your turn, use the ramp and get off as soon as possible.
Boats are supposed to stop at the upper parking lot and take care of all rigging then drive down to the ramp and launch. There is a narrow hiking trail that gets you down several hundred feet from the upper parking lot to the ramp, very steep and narrow, NO way to carry a boat down, even a kayak would be tough. The paved road is very long, very steep and full of blind corners. I wouldn't consider carrying a boat down that route either.
The ramp is the busiest between 7:30 and 10:00 AM. During peak times they expect you to be on and off the ramp in 10 minutes max. (the pro guides are much quicker than that!) Take a little more time and you will catch grief from the guides, the locals and the ranger on duty. Seriously, leave your truck unattended to take a pee during busy times and you will get in a rash of trouble. Take more that two tries to back your trailer in and you will also catch grief. Noobs are not welcome during the morning rush and they will let you know.
After 10:00 AM it's a different story. There is a vehicle waiting lane on the right side, during off peak hours they have let me park there and unload raft gear to the dirt area next to the ramp. As long as I wasn't putting gear on the ramp they were OK with me rigging there and taking some time.
There will be lots of empty flatbed trailers and shuttle drivers parking at the upper lot after they launch boats. You might find someone willing to shuttle your 'ready to launch' boat down for a few beers. Or hire the trailer with launch through Flaming Gorge Lodge or Trout Creek Ltd.