Great tip page Lou. To emphasis some your points, 2 years ago we were lucky enough to get a full Hook up site, but our 30' of hose didn't even come close to reaching the sewer. We went to Wal-Mart and got their last hose extension. We also met a fellow Goshen Rally-er there who was desperately looking for a 50A/30A adapter, but those were sold out long be for she got there.
Another tip...last year, were in the "Hobo pasture" and our site was quite unlevel side to side. Our "Lego" leveling blocks didn't work well because the ground was to soft. After quick trip to Menards, I returned with a 2X10-6ft and was able finished my set up.
It's odd, but considering that we will be near ground zero and the center of the RV universe, there is a surprisingly limited number of RV dealers and retail parts suppliers in the Goshen area.
We did observed in normal FROG fashion, fellow rally goers helping each other out with extras items if they had them, but as Lou stated, it's best to come prepared.