I managed to get my hands on an assortment of nylon standoffs so I can finally attach the two PCB's to the goggles. Also acquired a hot glue gun for sticking the standoffs down.
At first I would try and put some glue on the end of the standoff and quickly try and stick it down with the board attached, but then I realised how inaccurate the placing would be. I also quickly found out how annoying using a hot glue gun is.
This stringy sticky mess would end up everywhere. I decided the best way to do this would be to mark out the standoff holes through the board and onto the goggles, followed by sticking the standoffs down to these marks and finally screwing the board on top. This proved to be the most accurate and less annoying way to go about this task.
It took a little longer than I expected (1.5 years and 30 minutes), but I'm happy with how it's holding - although I am thinking in any future project that I will probably screw the board/standoffs into the plastic as opposed to using an adhesive, as the glue may not hold indefinitely.