There are only a few bike rack manufacturers that build bike racks specifically certified for use on the rear hitch of a travel trailer or RV. Check the manufacturer's website and product manual. Read the details carefully!!! Some manufacturers will state that a bike rack is approved for RV use, but not on a travel trailer. If the product doesn't say its certified for "Travel Trailer" use, don't use it on the back of the Trailmanor. Don't assume certified for "RV" use equates to certified for "Travel Trailer" use!!!
To build these bike racks to withstand the added stresses to be on the back of a Travel Trailer - you're just going to have to pay more.
Keep in mind that the bike rack hitch on the back of the Trailmanor is certified for 100lbs. Average bikes weigh 30-45 lbs. You don't want to buy a bike rack that weighs 60lbs and then put (4) 40lb bikes on it. Do the math and be safe.
P.S. Best one I could find for the Trailmanor:
https://hyperax.co/products/volt-rv