Trickle charger will see the 2 parallel batteries as one big battery, should work fine. To avoid overcharge, search- "Smart Battery Maintainer" several available. such as-
http://www.wirthco.com/documents/pro...ales_Flyer.pdf
Some RV's have an Emergency start switch which operates a relay connecting the chassis and coach batteries together as a starting boost or if one of the batteries is discharged.