I think that the OEM rims fit fairly tightly around the hub (actually more than they should). Our rims are designed to be lug centric rather than hub centric so they should actually have better clearance.
All that means though is that you should also apply your penetrating oil liberally around the hub, not just around the lugs. Sounds like you alread have that covered though (pun intended).
It may be worth a stop in to a local tire place and get their opinion on removal. I'm sure they have tricks up their sleeve that I'm unaware of.