For the mat poking out, use extra velcro fasteners along the edge, it will hold it down. I think I ended up using 5 more, because it was too annoying for me. Now it lays perfectly.Did you buy the Taptes Trunk protection? How did they work out? I couldn't decide and now have the car... [EDIT: Reviews for TAPTES are less than glowing... I may keep looking]
I just put my Tuxmats in (they had been in a box since shipped last time I posted. They fit is good most places except the driver side. The mat that lines the bulkhead to the right of your right leg bows outwards. I've left the mats in and hopefully they will soften and fit but if not, it would be annoying to constantly have the mat against your leg when driving. (I took out the Tesla carpets before installing. I also noticed that the mats sit a little higher than where the plastic meets the carpet (have not put clips in yet).
In terms of the TAPTES trunk protection, I absolutely love them. They fit about as well as I could hope. Now I will say, if you plan on moving them in and out frequently then I would not buy them. They will pull up the carpet because of the velcro, but they have kept spills in place, they cover the back of the seats as well for when I have had to haul lumbar (although I also used a tarp). I would buy these again in a heartbeat. This is how Tuxmats trunk mats should be.