Split rim tyre pressures

Just taken the troopy on its first sand run to experiment with tyre pressures and handling. (Standard tyres, on split rims)
Fully laden troopy has 70psi rear 50psi front for sealed road. Don't know what it should be for bush.

Noted that at these pressures it needs to be scrambled up rough steps - otherwise it will lose traction and momentum.
Noted that it felt very susceptible to getting stuck in dry river sand on 20 degree morning.

Reduced tyre pressure to 18psi all round for sand. This got me going - but not comfortable traversing across minor slope. The vehicle wanted to wander down the hill. A low speed it seemed to wallow far more than I was used to in the Prado (which also used skinny tyres - BFG AT). Higher speed felt just 'OK'.

Previously the ARB air pump inflated to 35 psi. With troopy it needed to inflate to 70psi ! At 8psi per minute, that's 5+ minutes per rear tyre.

So what pressures do the seasoned drivers recommend for sand/bush where there may be several inflations in a day's drive?

Oh.. also experiment was interrupted - when inflating the final tyre the air hose separated from the pump. No spares for repair. But fortunately it blew at 35psi.

This is all part of proving the car before adventures in January onwards.

(Shoalhaven near Nerriga NSW barely moving)

Best regards
Chris