Steel OTP List - Of Classic or Near-Classical form

What's puzzling about that? If you want a shorter wheelbase, there's probably enough clearance/room in the trackends to remove a link from the chain, and move the whole thing forward; BUT, that wouldn't leave you having to reinstate the link if you wanted to get a bigger chainring or sprocket.

I'm not that fussed about getting the wheel tighter in against the seattube, just not sure how much room it leaves for adjusting tension as the chain stretches. I had been considering getting some chain tugs, but I'm not sure they'd fit with things as they stand.

Anyway, as you say, currently I've got a little leeway on the gearing front; moving to a 17t on the rear will bring the wheel in a bit, and give me a bit more space in the dropout for tensioning.