While I've never camped at the TH near the Barcroft gate, I've noticed that often others have. I've found that driving times between the Grandview CG and the gate can be as long as 90 minutes, depending upon road conditions. The road is paved up to the Shulmann VC, but not beyond (or at least it wasn't the last time I was there 2 years ago). Depending upon when it was last graded, it can be quite rough, and the rocks sharp - seen lots of vehicles with flats.
Always impressed with how many marmots there are at the Barcroft gate area, and for the next couple of miles heading towards White Mtn.