How many marathons have you run?
It may be a plus not having to regain fitness, but maintaining a high level of fitness between now and FLM 08 is a pretty punishing mental routine.
I am just plain old, but for my money it is worth allowing the fitness to slide for a while to give the head a rest. Less mileasge, more speed for the 10k's and the 10 miles, and take it easy for a couple of months. Then it is easier to say, right, new season, only 6 months (or 5 or..), and I'll stick with the early mornings/lunchtime runs whatever to get the miles in.
On the day, running a marathon will make demands on your head, but that's nothing in comparison to the mental stamina required to meet a tough training schedule. Give your head a rest.
3 is therefore my choice. I'm doing the same sort of thing at the other end of the running spectrum. Since Connemara I've hardly run over 4 miles, but I have worked quite hard at running fluently and keeping feet active. Yeah, it's a pest, having to reconquer old ground, but the possibility of running freely instead of my old hobble is exciting enough for me to persevere with the plan.