I believe a sign at the bottom (at least on the east side) gives a maximum allowed 'kingpin' length.
Mono county just posted a report about allowed lengths on this stretch of road. It says the warning sign is for 30ft KPlength, and they propose prohibiting ones longer than 35. Seems trucks (semis) getting stuck on uphill curves is a real problem. Of hand I didn't seem mention of RVs.
http://www.monocounty.ca.gov/sites/default/files/fileattachments/RPAC%20-%20Bridgeport%20Valley%20RPAC/calendar_event/4034/truck_restriction_technical_report.pdf
