Do you know what size of the plexiglass you need?
I wonder if one could put
3M command velcro strips on the edges of the acrylic plexiglass, for the inside, and then attach it to the panel. I literally use command strips for everything. They're easy to take off, and to put on. I love the strong velcro on it. And they are strong enough to handle 3 lbs per set, one box having three sets (6 pieces). Not that the plexiglass is 3 lbs or more. it is probably way light than that.
Maybe I could do this too. Hmm...