How many of you have used the sheet metal screws provided by some kits to attach the engine to the engine mount? Do they hold up, or work loose eventually?

I have always turned up my nose at this, but now find myself considering it because this Contender does not give access to the bottom of the mount (for locknuts), and I just don't feel like going through the effort of fitting blind nuts under there, even though I've done it before and know that would be the smart thing to do.

So, how do the sheet metal screws hold up? We're talking #8 screws securing an OS 70 Surpass on a GP nylon mount. The mount is secured with 6/32 bolts, FWIW... and I should add that I don't have the proper size (short shank) blind nuts handy. All I've got are some long ones.

Steve