Sniper and Trunk Battery help

The 18ga you mentioned fires up the coil to engage the alternator relay, so there should be no danger to it

What are you referring to "diode?"

This always starts a big "thing." I DO NOT generally "like" single wire alternators for a few reasons
1.....Because they are one wire, this means that the SENSING (is almost always) on the main / only wire. THIS means that the charge wire must be somewhat OVER size because voltage drop on the charge wire is going to affect system voltage
2...Because it is one wire, disconnecting it--in an emergency--is going to cause a spike situation. 'I guess' the disconnect solenoid is supposed to prevent this, is it advertised as such?
3...At least some EFI systems (Holley, one) specify the main large power conductors go DIRECT to the battery. If you are racing, IE NHRA you might want to look into this, but I THINK there is now some "leeway" meaning this is considered 'OK' as long as they are properly fused, and that the disconnect actually does kill pretty much everything "else."
4...The Ford like solenoid in the Crackedback scheme only fires the starter......it is not used as a continuous feed

He and I sorta disagree on this, and as he has pointed out, "there is more than one way to skin a cat"
I prefer to simply run a large gauge wire to the Mopar starter, and use that also for the main feed to the rest of the car. No Ford relay. There are certainly arguments to be made both ways

Some "things."

You don't want to create a situation....especially with EFI, where a disconnect involving an alternator will "spike" the system
Many use a dedicated wire from the alternator to the battery. I claim this itself is unsafe, although it would avoid spikes
If you are going to a sanctioned (NHRA) track you need to meet those rules
In my opinion a better way is to use an "non one wire" so you can "break" the regulator/ field circuit--using a relay, which will avoid a system spike.