It's still doable, BK. There are more tents than RV's at Winfield (in fact, if you're looking to buy a tent, there's probably no better place to see every conceivable make and model on display, and talk to the owners!). If you have access to a camping store that rents good tents, that may be more satisfying than buying a cheap one, as the rental unit will likely be a sturdy, proven model. Many of the less expensive tents on the market either leak in the rain or blow over in the wind (or both!), and Winfield usually provides both conditions. Even so, lots of folks camp at Winfield in budget tents and have no problems, or have such a good time that the problems are insignificant.
A smaller tent has the advantages of compactness when folded up, relative ease of pitching, and better quality than a larger tent at the same price level. If you're not hung up on standing erect inside the tent, or storing all your belongings in it, a small tent can work out just fine.
There won't be any motel rooms available in or very near Winfield, but there should be plenty to be had in Wichita, and perhaps some other towns similar distance away. I encourage camping on the grounds to get the full Winfield festival experience, which includes some campground music around the clock. It's also a great convenience to have a place on site to retreat to for a drink, nap, etc.
Camping without electric hook-up is $7 a day (covers one vehicle and one tent). Showers are available, on-site in a semi-type truck trailer outfit (hot water, open top, sometimes long lines) or in town at a school gym or some such, shuttles provided. Port-a-pots are reasonably well distributed throughout camp, flush toilets in the main grandstand building in the stage show area. Water available in camp, though maybe a long walk. Cooking strictly what you bring. It's possible to get all your meals from the vendors there, saves some time and trouble but of course costs more than cooking yourself. Firewood available for sale.
The heart of town, with restaurants, stores, etc., is within walking distance, and shuttles are provided. My thought is go for it, it will work out. Hope to see you there!
P.S.--Where in MO? I'm in Kansas City.