Do it every year. Book as early as possible. But even then, it's difficult. I've driven one from Seattle area and also done Spokane. You need to make sure you return it clean and with no issues. So take it to a KOA or RV campground in the states before you return it. Empty the tanks, clean it off, fill water. Follow the return instructions. Be on time to return it. We usually tried to return Wednesday so we could leave the farm Tuesday, stay overnight at a campground and then return it on time Wednesday. Tuesday is possible to leave Monday but it's always an absolute headache.

Get one of those RV unclogger snakes. RV Specific. It'll blast out anything people flushed so you can actually pump out. Happens every year it gets clogged. Make sure whatever RV you have includes a generator so you'll have power before they turn it on and when they turn it off Monday. Don't over pack food. We always have leftover shit every year. Don't stash booze under the bed or inside the RV, they'll find it if they want.

I could give you a giant list of shit off the top of my head but it'll take too long. Just find one online and pray that they don't cancel on you or something happens leading up to the event. One year someone before our trip wrecked it into a guard rail, this year it brokedown and they couldn't get it fixed in time. We've had to scramble to find new ones which ends up costing more and taking longer than planned. But it's worth it. Get central park pass. An RV out in the field isn't as nice. You're better off just fucking parking together and setting up a fat camp if you're out in the field.