If you are going to load it to 7000lbs even most gas class A's will not be rated for that. Most all gas class A's are rated for 5000lbs towing while a lot of diesels are rated for 10,000lbs. Class C's are mixed as some can tow up to 5000 but some can not. I've never seen a regular class C with more than a 5000lb tow rating unless it was a Diesel Super C.
I understand your trailer is rated to 7000lbs but does it need to be loaded to that weight or could you still fit your needs only loaded to 5000?