New chart plotter combo

I’m looking to upgrade my chart plotter/fish finder combo. It will be a different size, shape than the one that is currently flush mounted in my console. I want to flush mount the new one in the same place. What is the best way to fill in the hole from the older, larger unit?
Thanks

A piece of 1/4" starboard as a backing plate cut the size of the existing unit, then mount the new unit to that with the propor cutout.

“Banana Pants”
Indigo Bay 170
90 Johnson

Walmart cutting board.

TexasAngler
180F Angler

How hard is it to fill the hole flush with the console then cut a new hole?
Or is covering the hole with starboard the best way?
I’d like to see pics of starboard covering the hole if anyone can post them.
Thanks