Just to clarify… the kind of pop-top I am talking about is not a tent trailer. Here's an example:
1973 Hunter Compact II - $3450
Depending on how they are equipped, they can be among the lightest of the fiberglass trailers. They also have less frontal area, which improves towing performance at highway speeds, and they fit into a standard garage. I have no idea how much effort is required to raise the roof, or if this would even interest you.
If you do look into increasing your tow capacity, it may involve more than just a rear-end swap. Suspension, brakes
, cooling capacity, alternator size are among the other factors that have to be considered. I owned a basic 4 cyl/stick shift Ford Ranger at one time and they're, well… pretty basic.