I can't help you with personal experience about Wildwood RV and Golf Resort as my own camping experience in the area is limited to Wheatly Provincial Park, about 30 miles east of there. I checked it out on the Ontario Private Campground Owners website and they have 4 1/2 stars on 5 for facilities and recreation. The OPCOA is a serious association and their ratings are generally trustworthy. http://www.campinginontario.ca/index.cfm?member=519-726-6176
I also checked it out with the satellite photography feature of Google maps and it is situated in the fields, with no industry, railroads or noisy interstates close, but it looks like there is little shade.
Depending on the number of days you want to spend in Detroit it may not be practical to stay on the Canadian side. (I do not know how close any good campground on the Michgan side is from Greenfield) Wildwood is about 20 miles from the Ambassador Bridge into Detroit, and this could be a problem as there are sometimes long delays for crossing the border. You have to know that the Ambassador Bridge alone carries as much bilateral trade between our nations as the whole trade between the USA and Japan. For info on the delays you can check the US CBP that gives wait times for entry into the US or the Canadian BSA that gives wait times in both directions.http://apps.cbp.gov/bwt/index.asphttp://www.cbsa-asfc.gc.ca/general/times/menu-e.html
If you like good wine, try a little detour to Kingsville, about 30 miles southeast of Windsor. There you will find Pelee Island Winery. Their vineyards are on Pelee Island which gives them a growing season two weeks longer than on the mainland, and their plant is in Kingsville. Their red wines are not very special, but their whites are as good as anything from France or Germany. http://www.peleeisland.com
If you want to stop overnight in the area between Buffalo and Windsor and you don't mind getting by with 30 amps/no water/no sewer for one night I can recommend Long Point Provincial Park and Rondeau Provincial Park. The camping area in Long Point is nothing special, but for the beach you will have a hard time to believe you are at a lake and not at the ocean. Rondeau has beautiful vegetation, a nice campground and a good beach. For more info and reservations:http://www.ontarioparks.com/english/index.html
This summer, you do not need a passport for coming into Canada or going back to the US. The earliest a passport is needed for land crossings is January 2008, and even this is far from sure. There are many smart people on both sides working very hard to reconcile the need for security and the need to impact cross-border traffic as little as possible. Nobody in the tourist industry in our two countries has any interest in impeding free movement of harmless tourists. So if your passport has not arrived before you trip, no worries, just come in.
Just make sure you fill your gas tanks before crossing into Canada. For example, today in southern Ontario Flying J sells gas for 0.99$ CDN per litre or 3.28$ US per gallon US, Diesel for 0.89$ CDN per litre or 2.93$ US per gallon US.