I did the Wolverine epoxy and poly flooring (2 coats epoxy, 1 poly). I have 715 sf, alredy divided into quarters by the stress relief cuts, so I don't know how well the coats would blend, but I don't think it would be a problem. Probably the best advise I can give you is to make sure that you coat it all. There are several places on my floor that I didn't roll out properly, and you can see that clearly.
Once you get done, good or bad, just keep saying to yourself "It's only a garage". That makes those chips and scratches easier to accept.