Ahh these rules are good. My island's bar would be fed by a mysterious spring, from which Guinness somehow flowed endlessly.
If I could only bring three, I would have to choose one Gibson - my '73 Triumph:
I would take my '83 Alembic, as it is a joy to play. Not a Gibson, but low-Z like the Triumph and has mahogany content:
And because I'm a synth geek and would also like a guitar handy, I'd consolidate and bring my '83 Roland GR setup, which again is Gibsonesque. Sort of a reverse Les Paul - mahog on the outside, maple on the inside:
Oh... and the blondes on the island would of course love prog, jazz, Zappa/Mothers, stoner rock, jam bands, etc...