[Griefbringer]

Back to the original topic of providing bunkers with AT capability, in the WW2 variant OOBs there readily exists a good number of bunkers armed with anti-tank guns. I haven't played SP:MBT for a while, so cannot recall how many of those appear in the OOBs there, but if you really miss them you could try editing the OOBs and adding an anti-tank gun bunker there.

Then again, if playing a long campaign, you cannot haver bunkers in your core force, so they could not gain experience - probably much more fun to play with regular anti-tank guns (and their vulnerability just adds to the excitement).