Moving to Caribbean.
Need mountain bike as general commuter.
100 mile long island. Bumpy roads. Would destroy a road bike. Also much sand in stretches.
I am 6'4", heavy, long torso, shorter legs, deciding on a bike. Will have no car, only this bike.
Island VERY hilly.
As theft is risk, and bike will be assailed by sea air, and because I'm poor, looking for entry-level.
Not like I'll be zipping along trails, hopping stumps, etc.
Longest ride will be 45 miles one way to extreme end of island.

Looking at 22" Giant Yukon in near new condition priced at $300. Is that fair pricing?
The one thing I really like about bike is crooked frame, in middle, so you don't hit bar or your nuts if you have to hop of rapid--it is also very windy on island at times.
Should I get hybrid tires or mountain bike?
What is the best super bright front headlamp?
What is a good rear pannier-like cage for groceries, laundry, etc. Nothing that totally impedes some adventurous riding.
Mudguards, anyone know a good brand that is sportier (not talking aesthetics but function).

Thank you for any time anyone can spare.
If there are any good bikes anyone sees on ebay for under $400 that are better deals, please advise, 22" or 23", I currently live near Seattle not that that matters.
I know road bikes, but not mountain, and am super grateful for anyone that has a minute.

LR