A quick peak under the dash - didn't look doable - will look closer at that.
One thought - If I rip the seat back off - a hole saw access point will be made.
Then LockTite for sure on those fasteners -
Under your dash there are 2 panels. The top one with the sub etc is removable with 3 screws. If you take that off you can lay under the dash and reach your hand up under to reach bolts for the bolster. IF IT WERE ME I would have a small woman or someone with smaller arms go through the speaker hole. Its just a total pita to "feel" with the end of a socket. I wouldn't cut up that area. Just make sure they are nice and tight when you get it back on. I gutted from the windshield back of my boat in the same amount of time that it took me to get 1 bolster out lol.