With any plastic ports, do not use Windex or other commercial glass cleaners. A chemical in these cleaners causes the plastic to craze prematurely. If you go plastic, go with acrylic. It is harder and less prone to scratch and more resistant to UV. Lexan has a softer surface so is much easier to scratch and is very prone to crazing from UV damage. Tempered glass may be stronger initially but breaks into a million tiny pieces if hit by a small object with enough force to break it. Vandals throwing rocks, bb guns, dropped winch handle or flying block can all leave you with a gaping hole. Safety glass may crack or even shatter but it will stay in place to give you some protection. The expansion of glass is way less than plastic making glass much easier to keep sealed. Definitely use butyl as a sealant for whatever material you chose.