I'm doing the same thing on my 10 as I did on the Cozy MKIV using two Odyssey batteries connected in-line with a busbar. A lead from the connecting busbar goes to the 12V master solenoid and the + terminal at the second battery goes to the 24V master solenoid. It works great on the Cozy. 24 volt handles the starter, fuel pump, landing gear, and the IP EFIS systems, radios, ect. The 12 volt side handles the interior lighting, power plug adapters for entertainment, and the 'el-cheapo automotive salvaged HID landing and taxi lights and some other 12 volt misc.. Used a standard Cessna style 3 pin aux power receptical wired to the 24V side for charging and emergency jump starting. It was a little weight penalty having the additional 12V heavy leads, extra solenoid, and an additional 16# battery, but there are absolutely no problems cranking over the engine due to a weak battery. On the 10, I flattened out the side lips of the supplied battery tray and rivited on 3/4" aluminum angle to form a boxed tray.. The solenoids are bolted to the angle and the dual batteries now fit perfectly side by side in the modified tray.