Update:
I've been leaving the house 5 minutes earlier than normal in order to get to the station earlier, thus allowing me time to walk a few extra feet down the platform and
hide wait in a semi-enclosed area. This also means I am getting on in a different car, which, for some odd reason isn't all that popular, so I've been getting my own seat every morning!

I've been doing this for about a week and it is working out pretty well in the mornings.
In the evenings I get on one car past my normal car and move away from the engine (as opposed to towards the engine, which is closer to where I park). I haven't seen him on the ride home at all... it's been nice.
Saw him again this morning. I was running late and saw him pulling into the station a mere 2 cars behind me. Grr... I hurried to get out of the car but he got out about the same time I did. I had a voicemail from the previous night and muttered something about needing to check it, and did. Somehow, I
ran away lost him between checking my voicemail, hurridly stuffing my $1 into the little box, and getting on the train, and then managed to find an already occupied seat to sit in. I don't think he sat in the same car as me either. I scooted off the train before he did and walked to work, thankfully, alone.
So far, the avoidance tactic seems to be working, and I'm feeling less and less bad about it.