I'm jealous you have rm 18s. I called probably 20 stores/websites this winter and couldn't find a single one.
I would definitely avoid over-watering them. I put mine in netted pots that were exposed to much more air than the 18s, and I was only having to water them once a week. I kept my room at about 74 with a soil temp of around 71. I was initially only watering by letting water wick up though the bottom of the pots. I would try and do the same.
How long did you let your seedlings vernalize in your fridge?
Here are my seedlings after 4 weeks of being planted in soil following 12 weeks in cold storage: