To be honest, I've never even considered going with 'as printed' for these kind of track numbers, because that's something that personally I really want consistency with (in terms of tagging). I never even thought of leaving it up to the artist/ packaging designer.
I'm not dismissing it though, it's good information to store (although does it really help people find a release? and if I upload scans as well we're not losing information are we? common alternate tracklists...). But I dunno. Most LP's don't have any numbers on the back anyway so by adding a letter we're already doing some sort of standardization.
Guess we're split on this one huh?
Leaning towards always putting in a number, largely because of the example where there's one track on one side, and multiple on the other - doesn't hurt to put the number in.
That proposal doesn't cover this question (one track per side, what format to use), so maybe we can nail it down here.