Ignition 12V Feed With Isolated Batteries

Hey everyone. Planning some wiring for a project vehicle which will have isolated dual batteries, and am finding myself stumped on the best solution for a 12v Ignition feed for certain devices. The isolation will be through a Blue Sea ML ACR voltage sensing isolator. The vehicle is getting the VAIS Tech SEER push button start system. This kit becomes the new ignition switch and has an Acc 12v output, and Ignition Output, and a Starter output. I would like to keep certain accessoties on the auxiliary battery to save the starting battery from being drained prematurely. One accessory in particular would be the headlights/running lights. Since they will be controlled by a DEI 545t, I am having trouble deciding where to take the required Ingition 12v input that the 545t uses to turn itself on. (It has a constant 12v input, ignition switched 12v input and ground). I am aware they will shut off automatically, but they can still be left on if the headlight switch is used. There are several other accessories that will be on the Aux Battery and also have an ignition 12v input. The 545t is just one example. Would there be any issue in feeding the 545t's Ignition input from the Push Button's Ignition output feed - which itself is powered from the main #1 battery I wish to have isolated from the 545t (Ignition 12v input and constant 12v input each from separate battery sources) In my drawing, I did my best to illustrate this as well as a possible solution using a relay. Pin 86 would come from the Push Button' Igntiion 12v output feed to trigger the coil. Then pin 30 COM and Pin 87 NO would join to send 12v from the Aux Battery #2 to the 545t's ignition input. With the Relay option, is there any point in a standard 5 Pin relay where the voltage on the coil (86) is connected to the voltage between pins 30 and 87? (Thus joining the two batteries and defeating the purpose of isolating them). Pardon my poor art skills and if this is an obvious situation. I'm a bit overwhelmed by all the wiring of the various products I have had to learn recently. I appreciate any feedback greatly. Happy Holidays!