in a conversation with jason back in Oct, he was mentioned flattening the track, putting down some specialized substrate that is compacted. this material would also enhance drainage.
he showed me some carpet samples then and asked one type, if i thought 12th cars could be run on it. imo it looked runable, in the past i have run 12th cars at indoor tracks that weren't Ozite/felts type. with astro going down now, i would say no.
onroad racing on astro? if the track will be flat and jumps are portable and removable with ease has me thinking in terms of TCs though. maybe 21.5 or 25.5 VTA TCs might work with a spec tire.