We play from 4 until 10. It wouldn't be as much of a problem, if you can be active on the website during the play week. I set up a system where players can earn XP even if the yare not at sessions for posting a journal for that week. Sort of like your character progressing off screen.
Showing up is great, but showing an interest in the campaign is what the group really enjoys.
We have another player whom is on call (doctor) at least once or twice a month, but still gains xp because of his activity on the board.
We also play mutants and masterminds one sunday a month so you really might just miss the one session a month. e-mail me at dungeonm at chrystaria dottt com and we can talk more about it.
Let me know what your playstyle is and what type of campaign you are looking for, and what your available sundays are and we can go from there.