Wautoma (Y50) seemed to be pretty accommodating. I happened across it as I had a room in town and a rental car after parking my plane at MSN. I curiously drove out to Y50, and found a newish terminal with a shower in the bathroom and reasonable fuel prices.
The manager told me that they had 50 or more planes camped there on Saturday night because they couldn't get into OSH.
Madison (MSN), itself, had a pretty accommodating attitude for a "large" airport with a restaurant on site and large concrete parking area. Overnight parking was $10/night, but camping wasn't an option. Plenty of hotels and restaurants were nearby.
Further south at Monroe (EFT), the fuel price was good. I'd specifically flown in to refuel before heading farther north. The newish terminal building was comfortable enough and had plenty of ramp space. I didn't check into hotel or food options.