OK, I usually get flack for this but there are things you can do to beef up your Minivan. The first thing I would do is install a quality aftermarket transmission cooler. They are surprisingly inexpensive and not too difficult to do. I would do that towing anything other than a popup because the majority of the stress on your drivetrain is going to be wind resistance not weight (well, unless you live somewhere with a lot of hills).
You can go to a good metal shop and see what they say bout your hitch and mounts. Sometimes, they can be strengthened. Your Minivan is not on a frame like a truck so you can only go so far in this department. Your ability to control driving habits can come into play.
You will need a very good and very properly setup weight distribution setup not only to alleviate the weight resting on the hitch but to keep your front wheels firmly on the ground in that front wheel drive van.
A good brake controller is a must as well. Don't play with some cheap time activated "proportional" controller.
Really though, you may just want to embrace the power of the popup trailer. They can be quite nice.