Most gas coaches only have a 5,000 lb hitch. You have to look at the chassis rating as well. Sometimes the difference between the GVWR and the GCWR is such that you cannot actually pull all 5,000 lbs. For instance, our 2016 Newmar Canyon Star has a GVWR - Gross Vehicle Weight Rating (the weight of your MH with you and your stuff inside and a defined amount of fuel and other fluids) is 26,000. The GCWR - Gross Combined Weight Rating is 30,000 lbs. So since my MH with us and our stuff is pretty close the the GVWR, we can can only tow approximately 4,000 lbs and stay within the GCWR of 30,000 lbs.
Your Lexus is around 4,300 lbs, but if you also carry "stuff" in it, that could push it higher.
I don't know if your Lexus if dolly towable - might be worth checking. Typically FWD cars are, but definitely not AWD. Check your owners manual.
When we started out, we did not have a car that was flat towable, so we got a dolly to tow our FWD car with the intent of selling the dolly when we eventually upgraded to a flat towable vehicle. Using the dolly was ok, but can be a PITA sometimes. We made do, but now that we have a flat towable toad, we would not go back to dolly tow.