Building a new tray for battery and ignition, using smaller than original battery.
Ignitech module would fit fine next to battery, any issues with that?
Isolation needed inbetween, if so what kind? Foam ok?

I've done that for years on bikes with no issue .
I use the foam with adhesive that comes with the Shorai battery or some of that blue insulation type foam.

Buy a good battery though.

I've done it as well.

If you're using a lead-acid battery, might be good to set it up so in a slow speed drop the battery can't squash it.
I've been running Shorai with mine, and those are so light I've no concerns with them.

You planning on using a Lithium battery?

Great, thx guys.
Yup, Shorai foam is very good. Will secure it w a strap.

Planning on using a spare from the Multi, either sealed or if I could wake up the Shorai
that was dried due to a bad reg/rec. I had it on a low power acid charger for 20 minutes,
jumped to 13V, canI just charge it w a lithium charger now?

I use an optimate lithium charger with Shorai batteries. Works better than the Shorai charger.