External gaskets to seal against DG units

[Robbox]

Hi, I have a couple of old UPVC units with a white external fir tree style seal. The seal has shrunk over time and discoloured, so I'd like to replace. White ones are not that readily available, but a local company, who replaced a blown unit, told me they sometimes use neoprene strips, with adhesive on one side, when a suitable replacement is not available. Then the glass is pushed up against the neoprene creating a seal. I imagine the strip is placed so that it aligns with the upper edge of the plastic beading.
What do we think about this idea?

 

[crank39]

Definately not if its external as its not waterproof, only really use glazing or security tape when the frame is externally glazed so the tape will be inside. White fir tree isn't common nowadays but is available still....

White E Fir Tree Upvc Glazing Gasket Weather Seal Door or Window 6mtr

White fir tree type e glazing gasket

upvcspares4repairs.co.uk

 

[Robbox]

I thought neoprene was a closed cell and would not allow moisture through. I know the current gaskets are not entirely waterproof as the internals around the glass unit is damp.