Thanks Nohuhu. Epic was certainly how it felt. I still can't believe we managed to get there and get through that cleft.
The two closest points to access BI from the mainland are either Sandy Point or Little Gibber. Both require 4WD with tyres deflated as the sand is very soft.
The track to Sandy Point ends in a carpark one dune back from the beach. You are not allowed to drive on the beach North of Little Gibber. The dune is smaller now than it was when I first visited and wouldn't be too much of a problem.
You can drive on the beach South of Little Gibber and that is what we did this time. Little Gibber was nicely protected from the ENE swell and launching was easy. The drive along the beach was a real challenge with a trailer in tow but we got there. The Prado was doing it tough dragging the trailer through the sand, especially as one of the trailer tyres was completely flat. I must have let too much air out and it broke the bead!
Didn't roll off the rim though.