I would have tried it if it were me Bhg, the splitter/combiners are not expensive after all, but I wouldn't like to send Barry up a cul de sac with a "should work" solution. Barry himself is pretty clued up anyway, going by past conversations, and will likely make a choice based on what suits him.
barry - that is a perfectly good cable but I'm surprised you don't have one knocking about as you seem to get one included with new routers etc. I have loads of them.
barry1010 - an ethernet card could be added, using a spare backplane slot, and the WiFi card left in place (and perhaps disabled). But if the latter will be redundant then I would use its slot.