I'm a bit slower than you but in my experience slapping my feet against concrete (well, tarmac) for 4.5 hours has resulted in no blisters, bleeding or bruising for me. Maybe before another marathon you could trying taping hotspots for your long runs - I know you said you don't get problems during long runs, but it would make sure that the taping didn't rub.
I did a lot of ballet when I was younger (stick with me) and they used to recommend that you rub your feet with white spirit to harden the skin - you need to do it every day for a while to toughen it up so also too late for this marathon but could be something to try for another time.
Ideally, you'd have tried out taping / using plastering in your long training runs so you'd have practiced and would know what worked. Do you not get problems in your long runs? I wouldn't advise taping for the first time in your marathon because tape can move around / wrinkle up and generally cause more problems than it prevents. Lots of vaseline / bodyglide might help though, on toes and any bits that you know gets rubbed.
Hi booktrunk - these look great, nice photo! I'm always on the lookout for shorts with pockets. May I ask you a question about sizing? I see you say you've got size small - is that a 10 do you think? And how would you say that compares to other clothing sizes? Hope you don't mind me asking