I'm unsure how strictly we're to interpret 'within', in the preamble, and I really don't like a 3 letter reversed possibility in row 7 - is that strictly 'within'? If it is, there's a better 'overhanging' vertical option in column 2 (an alt spelling) and as the single reversed example is so messy, I might as well opt for the vertical option.
Perhaps I'm taking the instruction to draw the decagon 'through the cells' too literally - drawing around the cells would get rid of the 'within' problem altogether.
However, I'm really tempted to go for the 4 letter option that's duplicated in rows 7 and 8 - we're not expressly required to avoid duplicates, just to keep to 'distinct rows'.
I'm not at all happy with this endgame - any thoughts would be very welcome.