I spent a little time looking last night, but all I could find was flat head hex socket. I won't need 50, so I'll have to keep looking for some I can buy just a few of. This points me in the right direction!
If you don't get the stainless self threading trailer deck screws in Torx, don't bother. Self threading means they are hardened and very tough, you won't break them, strip out the drive, or strip the threads.