[SkunkBoat]

IMO;
You are over-thinking/over doing it with the battery. Leave it where it is. I ran a V20 cuddy with zuke DF140 on a single Grp27 Dual Purpose battery. Did that for 12 years. Replaced the battery about every 5 years. I did not even have a battery on/off switch.(although I would recommend that).
I had two sonar/chartplotters & VHF. I fished at night with lights. I ran 60 miles offshore. Kept boat in water all season.

If you need 2 batteries for peace of mind, an ACR will work but you might be able to use an aux charging wire from your DF140. With 2 batteries you need to decide how to rig it. Are you going to use one for HOUSE 12V and the other for dedicated Start battery? You going to use a 1/Both/2/OFF switch?

BTW, If your battery ever goes underwater you have bigger problems than what happens to the battery.


As for the 7" display, get some 1/2" Starboard and make a new flush mount dash.

You say "DF140 2 stroke" A DF140 is a Four stroke. A DT140 is a Two stroke


I can't see your diagram post...