For my 2021 purchased in January I went with this mattress. An inflater inside - the mattress pumps up easily, seems tight enough to not sag/give through out the night... https://www.amazon.com/gp/product/B08LVJ47MM/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1
Move the passenger seat forward, in the rear floor board this square so I do not have any sag using the full length of the mattress... https://www.amazon.com/gp/product/B07YDT9YD2/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1
My planned bike events were cancelled, I have not tried yet overnight but in a dry run I am sure it will work well.