New JAYCO 154BH Baja Edition Owner

[Jasdoc]

Was looking at small trailers for me and my wife, lived the look of the T@B trailers, but realized they were just too small. The 154BH caught our eye, and we pulled the trigger. It is our first trailer, thought we would see how much use it would get before moving to something larger.
I am looking for good sites on regular maintenance, preventive, keeping trailer at its best. Also looking for any good "must have" accessories and camping checklists. This will likely be a weekender, no extended trips, and will occasionally have a grandson along.
Any good suggestions for replacement twin bunk mattress or 60x80 queen maters that can folded and stowed during the day? We were thinking just a 4 inch memory foam on top of the cushions

Thanks!