I was just there this year over Memorial Day weekend. I checked in on Sat. at 12 and my requested site was not available, so I told them to give me whatever was ready. We checked out the Tuesday after Memorial Day. I was hopping everyone would leave by noon on Memorial day which is why added an extra day. Some areas and loops were a little more emptier on the holiday (like the Premium sites), but the pool was still packed etc. And our loop (1900) stayed full the entire time with maybe only one or two sites empty. By Tuesday morning however it all emptied out. We stayed longer than we should have, but it was the first time since they put the new slide in at the pool that DH and I had been there that we could actually use the pool and slide without the pool being crowded and full of kids. We probably should have taken another vacation day and checked out on Wednesday instead. So, I think you checking in on Tuesday and staying after that will be a WHOLE heck of alot more peaceful and less crowded than coming in the day before. I mean keep in mind the kids are out of school in most places by then so it won't be empty, but you won't have to deal with the holiday crowds at the Fort either.
Next stop for us, Labor Day weekend. Checking in Friday (late in the afternoon) and staying through Wed. as of right now anyway. LOL!