I'm just coming up to speed with Masterplan, and it seems to me that it's better for home-brew campaigns than published ones like WotBS, which aleady has everything so well laid out. We also prefer to use figures and printed maps for our encounters.
I might stick with DnD4e Combat Manager...
Thanks for all the good advice. I checked the characters and discovered that they were actually level 2 - halfway to level 3 - so the problem isn't as big as I thought.
So, I'll just give them the "lite" version of episode 1 (using OnlineDM's plan), scale the encounters to match party level...
We've about to finish the WOTC intro scenario Keep on the Shadowfell, so the characters will be level 3, and there are seven of them. This probably puts the party at the start of episode 2. Has anyone tried starting at this point?