The P68 is an old aircraft...and from my memories of flying it so many years ago, it was even old then, it was stinking HOT (admittedly Nth AUS), and the passengers hated it due to the fact they were squashed in (and in our operation we had removed one seat!!).
Also when the engines were hot, they were a bugger to start.
IMHO, tourism deserves at the very least deserves a high wing Turbo Prop aircraft, like the Caravan.
My 2 cents.
Good luck with your venture.