I had the same problem - after table was fitted the other day I was on some rough bitumen and thought I must have a truck load of scrap metal bouncing around in the back. Didn’t realise what it was until I opened the big door to check and on shutting, it heard the dreaded clanging. Gave the tablet a few thumps and found out it was the culprit.
Considered bending then tabs in a bit, but they are fairly solid, and as the slide latches only just sit behind them by a few mm. at most, it would reduce that catch area.
After buying some rubber as you suggested, when I went to fit it, I noticed that some mounting screws along the bottom were not done all the way up which allowed it to vibrate.
I also noticed the rubber bump stops had locating bolts behind the unit.
Tightened the bottom screws, undid the bump stops and spaced them out with washers, and bingo, closes firmly with no more rattles or extra padding!
