I got a roll up cover from amazon
Tyger Auto TG-BC1T9039 TOPRO Roll Up... https://www.amazon.com/dp/B01LYYJIYF?ref=yo_pop_ma_swf
Looks good, works on the rail system or not (has clamps for both)
Rolls up against the cab when you have an oversized load .
Tyger Auto T1 Soft Roll Up Truck Bed Tonneau Cover Compatible with 2007-2013 Toyota Tundra | Fleetside 6.5' Bed (78") | TG-BC1T9039 , Black https://www.amazon.com/dp/B01LYYJIYF/ref=cm_sw_r_apan_glt_fabc_GMYWXEFKM97PFPX4D2J4
Would something like that work?