Sure.

They are horizontal dropouts, what I didn't mention is that there is no derailleur hanger mount. So nowhere to hang most chain tensioners. I agree that in theory you just set the chain tension appropriately and all is well, especially if the bike was a commuter. Even though the bike has solid axles (i.e. not qr) I had problems with keeping the tension where I wanted it, partially because of the heavy load put on the drivetrain (I'm no Cavendish, but as I often find myself pedalling as hard as i can manage in the lowest gear the axle eventually crept forward). A cheap set of tugnuts fixed this for a while until they broke - I now have a Surly tugnut which is doing a pretty good job keeping the axle still.

I still have problems with chain stretch though (yes - I know it's the holes getting bigger, not the links stretching). The chain has to be pretty firm as the bike is thrown side to side so much. I have to keep a close eye on the tension - having it as tight as reasonably possible. (set it too tight and it will eat bottom brackets of course)

I found an emount chain tensioner online ( Yess ETR-B ) but they seem to be listed as no longer in stock.