Thanks everyone for your feedback, I'm going to try VPI felt mat to start. Worst case, I'll use it as a dust cover :)
@tablejockey , I tried using VPIs stainless steel screw down clamp with rubber gasket, but I don't find it performing any better than HRX weight with warped records.
Most of my warped records are warped around the outer perimeter, and clamp does nothing to flatten the outer edge. For other records, HRX is just as good in keeping center section flat to the platter, without the extra effort. However, I'm also not ready to pay $1k for a perimeter ring, and for 45rpm it's not worth the effort.