Headlight conversion - lights fitting question

[TVRwhoa]

The cerbera body restoration is now in full swing and we have fitted the headlight pods in (fibreon) - when I had a thought about how do the lights fit in - in the back of the pods - I know that there are metal discs which have to go onto the back of the pods to accept the 90 mm lights - but then had a nightmare thinking do they have to go on before the pods get glassed in (fingers crossed they don't as mine haven't been).

Could someone help please for pictures of how the discs fit on the back of the pods and whether it can be done through the inspection hatches.Here's hoping or I'm going to be having an awkward conversation.