When I went, I stayed in the town of SHEBOYGAN and drove out to Oshkosh; about a one hour drive. In Sheboygan there are the usual Holiday Inns etc. and there doesn't seem to be any problems with obtaining accommodation at normal rates. There are plenty of good restaurants in the town. The queueing process at Oshkosh, as mentioned earlier, is orderly and relatively quick for such a large event.
I hope you enjoy it!