This may be out in left field, but a P365 would fit well in a holster in the lower (mid-upper leg) pocket of cargo pants. Just switch from the belt position and place in the pocket when seated.
This exactly how carry my p365 when making extended drives. The transition from the pocket to iwb holster and vise versa is easy to do in the car. You could also just keep it holstered in the cargo pocket although it does flop around some what. I use a Recluse cargo pocket holster.