Well, my thought was if I was going to have to add another relay, why not use the solenoid wire for a trigger and use some #16 aircraft wire down to the solenoid. That would give an even bigger smack upside of the head to the solenoid..
It may not be necessary though, and your method would be considerably easier. It's cranking better than it ever has, even with a depleted battery from fooling with this thing all day. What are a couple of more wires to that birds nest on top of the battery, anyway?