Err... the guy said "putting a small (300cc) aircooled two stroke as an
inboard in a small wooden boat". He didn't talk about enclosing it or
anything else. In fact he says "With adequate air circulation can anyone
see any potential issues here?".

Given his specifications (small boat, small engine) and that he has
stated that he is prepared to cope with air circulation problems what
are your concerns?


That he, like you, has grossly underestimated this issue.

In reference to the Honda, do you really think that the cooling
requirements on a two stroke engine is different from that on a four
stroke?


Absolutely.


Small gas engines of the utility variety ("lawn mower"engines) have long
been used as inboard engines in small wooden boats. Up here in the
Pacific NW USA, a local traditional boat called the Poulsbo (or Young)
boat was frequently powered with an air-cooled Wisconsin or B&S single
lunger. The Poulsbo boat usually was between 16 and 18 feet long and was
open. The motor hung out in the breeze.

These air-cooled four stroke engines were relatively slow turning and the
noise was only mildly objectionable. A modern air-cooled two stroke
inboard would need to spin at a much higher speed and would create quite
a racket.

Would a small, 300cc, two stroke inboard work? Sure but the effort would
be high and results may not be satisfactory. If the OP really wants a
small boat inboard, look for a vintage four-stroke. It might be more
practical to design/redesign/modify the boat for an outboard. A few of
the surviving Poulsbo boats have been modified to use an outboard, either
on a bracket on the stern (easiest) or in a well (elegant but lots of
work).