I grew up in Indiana, have lived in the Detroit area for 22 years, and work for a Canadian company, so I know these routes.
I would not go over at the Detroit border crossing (bridge or tunnel). The Blue Water bridge in Port Huron / Sarnia is normally quicker.
The 402 over to London, Ont. has had quite of bit of repaving over past several years and I don't recall a roughness problem.
There are two nice public parks a little out of way, north of the 402 up on the east coast of Lake Huron -- Pinery and Ipperwash. Both are "Provincial" parks. Check out
www.ontarioparks.com
Can't comment on private campgrounds since we don't use them.