I don't see why having the FP raise dependant on boost is such a problem. Now I understand you may be saying you don't want to run fuel pressure levels that high. So...
What's the FP setting for the Non-SVT FPR? 10lbs less?? What about the early Duratecs???
Rigging a switch/valve that is boost sensitive would work I suppose.
You could always convert to returnless.
