I think, buying an old single-seater Folbot or Pouch will be much less pain (of all kinds) and not much more expensive, considering that you wouldn't have to pay a sailmaker to shorten and sew again the skin. Assembling has always been a pain with all Russian folders, AFAIK - and unless you calculate and do all your alterations
very accurate, chances are that it will become even more difficult to assemble after the downsizing. Or less mechanically strong. Russian boats are not the cutting edge in design, besides, Taymen is a
very old model - 25 years or more, yet some engineering brain work was invested in there.
Agreed with Chris, 17+ ft kayak is not too large for a sailboat, especially with a schooner rig.
PS: I am a bit sceptical about reports on military applications of Taymen boats, particularly due to difficult assembly. Even though those that I've seen had factory-installed hull reinforcing strips, which warrants more protection for heavily loaded hull in unknown and unpredictable shoreline. Unlike, for example, Folbot GII, which have neither hull strips, nor grab-handles, yet reportedly have also been bought by the militaries (no reports as to the further use). Don't remember, whether Taymen has grab-handles - probably, not. Apparently soldiers were carrying those boats on their shoulders, 4 at each boat, like a casket
