OK, so here is what I have learned:
The stove when it left the manufacturer had the
shorter legs, requiring the protection as indicated in the manual that went with that model/serial no.
After it was purchased by the guy I bought it from, he installed
taller legs as with the model that needs ember-protection only. The stove's current dimensions match the manual for the
tall-leg model linked by
Dairyman, and
do not match the manual for the serial no. I have.
So it seems our professional was working with that information when advising us (so it could be that you guys were right in a way and so was he in a way).
I spoke again with the guy that I got it from and he told me that he had it on a pad that was plywood topped with 1/2" Durock and ceramic tile (as per the tall-loeg model's manual requiring ember-only protection). The tile never got hotter than "warm to the touch" while he had it burning for ten years.
I am going to check with Hearthstone to make sure that I am correct that the legs are the
only difference between the Heritage 1 8021 that DOES need the r 1.2 protection, and the Heritage 1 8021 tall-leg model that DOES NOT need that, and needs ember-protection only.
So it may well be that our new hearth is compliant with my stove as currently configured. Boy, oh, boy would I be happy to confirm that!
If not, I will probably go with the extender that
begreen kindly linked to for me, and then maybe embark on a better long-term fix next year (either tearout or new stove).
I am very grateful for all who have provided their input. I have learned a lot. (And forgot to mention,
Simonkenton, that the beaten copper is a really nice look.)
So ... any thoughts to share?