Matty - Just do it as they say!
I was only there for 3 hours but no regrets.
Try the Winair or Air Caraibes or St. Barth's Commuter websites and see where the deals are.
Obviously the Caravan has the front seat if you don't look like you'll kick the rudder peadals on t/off
Winair use the Twin Otter and BN-2 (was speaking to an Otter pilot and he says the view is great from the front pax row.
Not sure whether you can get a front seat in the BN-2.
Air Caraibes did a great deal on their www. but not for early dep from SXM and late dep from St. Barth's.
Air Caraibes www. is in French - I risked my former O'level standard and I managed to go on the right day! And for the right price! Actually we left early and arrived before we should have departed
For approval to use St. Barth as a pilot, you have to go in with an instructor from Grand Caisse on the French side of St. Martin - as opposed to Juliana on the Dutch side.
If anyone knows an e-mail address for the fying school at Grand Caisse....please let me know - I just have to make an approach to Rwy 10 at St. Barth's from the L/H seat!
Rwy 28 would be okay...but I can respect the guys that land on 10. There are 2 windsocks on the hills either side of the app to Rwy 10 - and don't they blow all over the place.
Go and enjoy!