If I had to drive around that issue I would try trail braking a bunch more in those turns right down to the apex.
I would start with zero rear toe with the expectation of increasing rear roll resistance. However, for an easy test of roll resistance you can unbolt your front sway and do a couple laps and see if that provides enough additional droop too keep the inside front tire on the ground.
Considering I run 600 and 750lb springs on a 2100lb car it stands to reason that you're way under sprung especially if you're on R-Comps or slicks. The lack of rear roll resistance could be reason of front tire lift and understeer and/or lack of front roll resistance means you're losing too much camber under compression (mac struts)... However I'd start by going around the corner with all 4 tires on the ground.
