said by IPtrans:it makes sense to put in a future proof solution with enough headroom to accommodate any usage growth
The OP hasnt even said what the boat house requirements are in terms of bandwidth.
There are no real details about whats even going to go on in the boat house, so whats to say a wireless link cant supply a decent enough chunk of bandwidth to suffice?
No one has actually discussed that, so no one can actually say.
said by IPtrans:it's crazy to consider wireless to be the primary and potentially only choice
Ive never said dont put fibre in, but to certainly give yourself the option to do so.
To me the burning question is why wireless isnt suitable - its a short shot (250 feet, 75 metres), so shouldnt require anything fancy on the wireless side, certainly not hundreds of dollars worth in my comparatively limited knowledge of wireless engineering.
For example, whats a pair of Ubiquity radios? Local pricing puts me at about USD$140 for a pair of NanoBeam 5ACs (up to 450mbps claimed throughput) which should at least cover the current Internet connection and then some...