2003 Eagle 10sg Hitch Wiring

[jadkerson]

I purchased a used 2003 eagle 10sg. The previous owner has cut off the factory 6 way plug and converted to a 4 way flat plug by disconnecting the red 10G charge line and Blue 12g Brake wire. He also cut/removed the 12v auxiliary battery cables.

I am trying to get everything back in working order and will be using a 7-way plug. I have the RED A and BROWN turn signals, GREEN Clearance lights, BLUE Brakes and WHITE Ground connected to the new plug but I don't know the correct connections of the RED 10G Charge line and auxiliary battery cables.
I assume the RED 10G Charge line connects to the 7-way 12V Power but as for the battery cables to the auxiliary battery, would the RED Positive post wire be spliced onto the RED 10G Charge line and the Negative post wire spliced to the WHITE Ground ? I also understand that an inline fuse needs to be added to the RED positive post wire. What rating of fuse should it be?
Thank you for any assistance you can provide.