Anybody know the criteria for being allowed to do the full race?

Entry form has a space for up to 3 AL or AM races, to prove competence.

I've got a BL and an AM race coming up in the next 3 weeks. I doubt this will be enough? Do I have a chance of getting in, or do I need to try and fit in another AM race, or should I just forget it this year and do the half...?

(my keen-ness to do the full race is due to being very familiar with pretty much the whole route...)