Its not too hard to do. I have a VP-540, I have done double sided, including a 20x4ft banner.
Smaller is actually easier because there is less room for them to skew.
Print em in batches of 4, create a corner mark at the zero position. make sure your feed is completely straight. print the banners, turn over wind back onto the feed roller (helps to keep the roll true). use a pin through the corner mark, when you turn over align the print head on the pin hole (good for most positioning). print the second side (remember to flip the design in versaworks so both sides are the right way).
You may get away with larger batches depending on the design and the need for exact backing up.
or you could outsource. It is good to know how to do it though.