Something like this may help : NO-FRAME Fiberglass Edge Coating for Frameless Acoustical Panels - Buy Insulation Products
Yeah...I know about that...and there's better/cheaper stuff. Just use Roman 543 (wallpaper adhesive)...it's the same and costs 1/4 the price of the other stuff...which many people say IS just Roman 543 diluted down a bit and poured into generic cans. There's also a heavy duty Roman 880, which still costs a fraction what the building supply people are asking for their "no-name" stuff.
It's mostly used for when people don't want to use any wooden framing...and it works pretty good, but there's a longer drying time, and with 50-60 panels, it would take a lot of room to lay it all out. I am keeping that in the back of my mind as an option if my own approach doesn't work.
What I'm going to do is simply make a smaller wood frame that will slide into the actual panel frame with just enough space so I can pull the cloth in, and that inner frame will allow me to keep a tight pull on the cloth until it's stapled down. Then I remove that smaller frame and drop in the insulation panel...and I move to the next one.
Of course...I will try it with just the insulation and see if I can pull-n-tuck the cloth and get it stapled, while keeping a crisp shape to everything...it might not be as big a deal. The acoustic cloth I'm getting is really good quality, made from polyester and the weave has no stretch to it...so it shouldn't be a fight to get it tacked nicely.