You really have no choice...or no good one. Add 2 more D27DC-160 12 volt units, or pull the existing ones out and replace them with 4 deep cycle 6 volt batteries. I prefer the latter, but my 335 came with 4 D27DC-160s and I ain't gonna throw all of them out.
Did your solar come from the factory? I am designing a system for my coach. What are they?