Totally understand where you’re coming from—must be tough trying to rest with all the vibration and no audio cues. The idea of using a 3/4 inflatable camp mat is quite clever! I’ve heard a few travellers with similar sensory issues use Therm-a-Rest or Sea to Summit mats—lightweight, compact, and decent cushioning. Just make sure it doesn’t raise you too high off the seat or push your body forward awkwardly. Might also be worth testing it at home first for comfort. Hope you manage to get better rest on your next flight—WT+ is a decent step up!