If it were me, and it has been a couple times, I'd drive to the lot assuming I can tow it back, with a backup plan if I can't. You have to ask yourself, "What will I do if I get there and can't tow it as-is?"
My backup plan is usually asking the lot manager ahead of time if I can reschedule pickup if immediate recovery is not possible. Then I'd come back with a hauling trailer (rental, borrowed, etc). It's a gamble and may cost more with multiple trips (fuel, rental, time off from work), so you have to weigh the costs. If the cost of multiple trips is too high, plan your recovery as if the trailer is not towable as-is and rent/borrow a flatbed or car hauler to load it on.
Most often in my experience, they're roadworthy at pickup, but it's just smart to check them out a bit instead of kicking the tires and hooking up. Every trailer of 9 that I've picked up was ready to roll except one, which has a wobbly hub that I still haven't looked into, but would not have towed. I did tow it around the yard to move it and it was fine at 10mph...
The hub re-pack suggestion is a pretty good idea, and will save you later headaches if the current grease is dried out and you pull the trailer 70 miles. Personally, I wouldn't want to get into that stuff in the GL lot unless I knew it would be quick and easy. God forbid I do something crippling to the axle while I'm futzing with it and have to leave it there in pieces...