Plexiglass is an attractive option for reptiles, however it can be scratched by the monitor's so it will become aesthetically poor over time. I'd recommend 1/3" panes or you can use smaller if costs or something makes an impact, by bracing/dividing the large panes into halves. By providing a proper aboreal perch and climbing options the animals shouldnt put too much strain on the glass. I'd check around other custom cage builders and ask them, many are willing to help no problemo