Worse comes to worse, the CG manager may have some boards to help out. Tell them it is your first trip when you check in and you'll probably get a nice easy access site that is pretty level.
My first time out I found a point in the site that was close to perfect, just pitched a little to the back of the trailer. Got everything set up, extended the slide and learned that it took that pitch a bit further. Luckily the fridge still worked, but I was concerned at first. I now make sure I am about half a ball in the gauge to the opposite side.
I have one set of Legos Amazon.com: Camco 44505 RV Leveling Blocks - 10 pack: Automotive
and I use chocks on both wheels sides of the un-blocked side. I have extra lumber in case all else fails.
I recall seeing another camper with a lot of wood on one side at one site. Really wish I'd taken a picture.
2011 PrimeTime Tracer 2600rls
2001 GMC Yukon XL 2500, 6.0L 4.10:1 axle ratio
Nights camping 2014 - 17
2013 - 15