Trunk Mount Batt. Opinions needed

I was running the Ford soleniod because my Positive cable runs along the left interior of my car. The Ford soleniod keeps this wire dead until turning the key. I did this so I dont have to keep marshmello's on hand if I had a short.
I could do as you suggest and then add a Breaker or fusible link for safety.
Nice Ride by the way. I miss my 70 Duster