finegrain... I bought a 6" diameter screw in hatch with a clear cover, moved the battery switch to an area that had enough room behind the bulkhead fo the switch and enough room on the bulkhead for the cutout and hatch, Even backlit it with a red l.e.d. off my courtesy lights! Now even if I forget the thing is right there staring at me and with the back lighting I at least remember when it gets dark and I turn on the courtesy lights.

SS another option is 2 series 27 deep cycles of the same lot and if possible consecutive serial #'s, hooked parallel. A lot of what I look at for myself is more for spending the night (or 2) on the batteries. If you are going out for the day and running an alternator or putting the batteries on the charger at the end of the day, your six cylinder and two 27 deep cycles makes a lot of sense to me

One thing i remember is try to never let the voltage drop below 11.3(?) volts. If it drops below that it is considerd one cycle. Deep cycles are rated on reserve minutes( #of minutes at a 25 amp load before the voltage drops below 11.3 ???) and cycles, Keep the voltage up (by adding batteries or going to a battery that has a longer reserve) and the cycles are not nearly as important.....