This link will give you a good overview of what UHMW is.....
https://www.interstateplastics.com/U...c&withinsite=1
The screws I chose after a lot of thought and looking at other OPs that had done similar repairs with UHMW are #10 SS wood screws 3/4 long... good grip strength and not too long to protrude thru flooring on top side
my hydraulic slide outs actually ramp up and onto a double ramp wear bar underneath the slide floor mounted inside the slide out cutout....
Image of the double wear bar.... I have seen NO evidence after at least 50 cycles in and out now with this slide as far as the UHMW strip snagging on anything... the screws were installed each with a dap of proflex on the threads to add a bit of insurance that screws would not back off...
the screw heads are countersunk about 1/32 below the surface of the UHMW.. and remember this material is ONLY .125 thick... I did not need to do any vertical adjustments to slide .. closes nice and tight on outside and inside..