A mate is there currently, reckons there's not alot of beach up Northern end of the island currently, even at lowtide. Ngkala Rocks inland track is deep talcum like soft sand at the moment, but he hasn't mentioned Indian Head track at all.
Low tyre pressures are the key for those inland bypasses, so no higher then 18 psi rears and 16 psi fronts like Proudy has already mentioned IMHO. The run up the beah to Indian Head shouldn't be an issue if you time it for a few hours before lowtide, then stop and check the tyre pressures before attempting Indian Head. I'd actually run higher pressures until you get there myself, then drop them for the soft sand of Indian Head.