An enclosed trailer rental requires the usual planning about trailer towing capacity that you make when you are figuring out just how much you are going to tow in the first place. First you must figure out the size of the trailer you are towing plus the contents you will be towing in the trailer. This has a direct bearing on the GVWR for the hitch. If your trailer weighs 3,000 pounds, your boat weighs 3,000 pounds and you have another 1,000 pounds in miscellaneous storage in the boat, including fuel, then your tongue weight will be 7,000 pounds and put you into the 7,000 to 10,000 pound range. If you also carry a full vehicle, that has to be factored in so that you will need at least 10,000 pounds of towing ability in your vehicle. It doesn’t matter whether it’s enclosed or not.
For more info, see Average Cost to Rent a Car With a Trailer