You did answer your own questions. Recognizing that marine ply is not
in the budget you will have to accept that the ply may not last as
long but 10 years ain't bad. I agree that it would be best to put a
layer of glass on, doesn't have to be heavy but it will give a lot of
increase in strength. System Three and I believe that West has a thin
penetrating epoxy. There is also a product out there I believe CPES
that is a thinned epoxy. In talking with the folks at System Three
their product has more solids and no solvents and still penetrates as
well. It is best to put a good coat or two of epoxy on any ply end
grain on a boat. Have fun.

Bria