Synyster

I would argue that it's too easy and not very fun. Maps like FIVE are much more fun as they are more challenging. In answer to your question, it depends on what you define as 'good' for solo. It's good in the sense that it's easy, but not good in the sense that it is very monotonous.

Do your catwalk idea, and have the person with Winter's Howl spam the thief with it. The thief slows down A LOT when hit by it and takes plenty of damage; have other players also shoot at thief while he is slowed down. Easy round and bonfire sale.

Person with Thundergun circles near the stage turret continously rounding up zombies, meanwhile second player simply hides to the west of the stage near claymores, only having to deal with a window and a few stray zombies (as long as the door isn't opened to the meteor rock). Worked a charm for me and my cousin, we got to round 50 with very few downs, then took a picture and suicided. I honestly think it's the best multiplayer strategy, because for 4 players its the same as the extra 2 players can hide near the claymores too and shoot into the hoard the player with the thundergun is collecting. Very fast rounds and very small risk. Hope that made some sense.