I think the Ford solenoid would be fine, but there are purpose built battery isolators that you might find more appropriate. Same idea as the Ford solenoid:


https://www.sherco-auto.com/handles-200-amps-continuous-and-300-amp-surges-durable.html


The problem with the battery isolator on a modern car is that you wipe out memory whenever power is cut. So no codes, no radio presets, various advanced functions would require new programming, clock, etc.


Elusive battery drains can be caused by weak diodes in the alternator. Disconnect the B+ lead on the alternator and see if that makes it more better. If so, you need a new alternator. It's always the last thing you think of...