These windows were glued in almost 20 years ago, and have stuck in place perfectly.
these windows are plexiglass. And were glued in place using silicone. There are different kinds of silicone adhesive. The key to success I was told at the time, is to use little pieces of spacer material to maintain a minimum thickness of the glue line.
In this case the installer used little pieces of plastic that were about 3/16' thick placed between the surfaces to be glued. The thick glue line allowed for the difference in expansion between the plexi and the structure.
Using sandbags should maintain the clamp pressure while the glue goes off. The installer that did the windows on the boat used blocks glued with glue from a hot glue gun applied to the surrounding freshly painted surfaces. these blocks were shaped to extend over the area where the plexi was going, then wedges were used to apply pressure. Once the glue went off the clamping blocks were tapped on the side to release from the painted surface, with out damage to the painted areas.
There are many types of silicone, and there is one formulated just for this application.
The problem with fasteners is the likelihood of cracks while tightening the fasteners in place . Or later when the structure if flexing while in action. Causing cracks radiating from the fastener wholes.
Hope this is helpful to you.
Cheers Rich