Underbody Panel Fasteners

My 22 R1T with All Terrain Package has been serviced many times for a variety of reasons. Many of which have required removal of the underbody panels.

I had a noise develop in the front end a bit back and when I went to take a look and removed the front panel...i found I have lost some of the fasteners and some of the u clips have been ripped completely out of the panel they are attached to.

It is kind of a poor design with a large variety of fastener types and lengths and it seems thru the variety of visits some end up back in wrong locations and some simply abandoned by service. Plus the factory seems to have used steel and many are corroded and I assume that is why the u clips end up ripped out of the plastic they are attached to.

Just wondering if anyone has noticed same and if anyone has made any attempt to correct and if so....what did you use to do so.