On Sat, 20 Jul 2019 10:27:52 -0700 (PDT), A K wrote:

I want to mount this piece of plywood in such a way that it is reasonable removable.

I first need to true up the edges of the wood and that is difficult because of it's small size.

I have a table saw, circular saw, and reciprocating saw.

I would like to avoid the table saw because of its weight and bulk.

How can I true up the wood?

https://imgur.com/iFZFKs8

A rasp (or sandpaper), a straight edge and a square.