Locally, everyone seems to run their VTA cars at or around the 4.2 FDR on an outdoor flowing layout with a fairly long straight. With the spec tires, that works out to a rollout of around 48mm. A 5.0 FDR would be about a 40 rollout -- probably ok for a tight track with a short straight. You didn't mention what car you have, but VTA cars are 1450gr minimum and boost is outlawed.
To your last point, I have often thought about putting my car down -- it would be the humane thing to do