I would open Silver/Trader here, and then look for some mix of feodum/province, depending on what my opponent does.
If my opponent tries to perform the trickery with stonemason/quarry/forge/trader, that would be totally fine with, because by the time he's ready to get feodums I already have plenty of them.
The fact that it works against Advisor-BM does imply you can have a lot of fun with it, but not that it's actually good.
Sorry to spoil the fun.