I have never camped in the Niagara Falls region but have visited many times.
The Canadian side is a lot more touristy with a lot of fun attractions, better access to the Falls themselves, and I am sure camp grounds that could handle your large rig and tow.
A suggestion I would make is look at "Niagara On The Lake", Ontario, CN.
It is a neat "little" town "just up the road" from Niagara Falls, Canada. There are a lot of neat wineries around Niagara On The Lake.
I looked at RV Park Reviews and didn't see a camp ground in Niagara On The Lake - - too bad but I believe there are some CGs close by.
Niagara Falls, ON Campground Reviews - Best of Niagara Falls Camping - RV Park Reviews
One thing to consider, the roads/streets in and around the Falls on the Canadian side are sometimes narrow and crowed in the summer season - - may not be good for a 70' rig and tow.
Also, check out the Canadian Customs as there are items you cannot bring across from the USA - - I am not sure but fresh fruit may be one item, you can check it out here:
https://www.cbp.gov/travel/us-citize...-mexico-travel
and
Canada Border Crossing | Rules, Regulations, Passports
You will need a current Passport for all travelers. Check out the exchange rate before you leave, most establishments will take American money in and around the Falls, but getting some Canadian cash might have a better exchange rate and you will get Canadian $$ back as change in most instances.
Niagara Falls region is a great place to stay. Not sure what your plans are for after the Falls, but Toronto is a short distance away.
Have fun - - be safe, great destination for a trip.
g