psi guide for sand,dunno about the uphill bit but this is what i learnt..

you should be able to back off go pedal(cant spell excalorator) and come to a rolling stop....gentle as easy does it...down here when i see sand it's straight to 10psi and to be honest even other places i go for 12...the hard bit about hill climbs is there is usually a lip at the bottom or the top so speed sometimes doesn't or isn't always an option..down here unless its callcup we just gently and easy..as long as ya have revs on hand you usually have aenough tourque to deal with most of the sand and hills here