and the 4000/4200/5200 adhesives generally do not work
so well on acrylics or polycarbonate materials.
Sika 295-UV is the one to use, that's its job, it does it well.
The underside surface of the teak should be primed either with the Sika primer that is commonly used for priming seams in teak decking, or alternately abrade the teak well, wipe the surface with acetone or alcohol and put on a thin coat of epoxy.
You will also use alcohol to clean the plastic surface.
You'll not require screws from below, but you'll want some weight(s) or some kind of clamping arraignments until product sets-up.
A lot of masking tape will be used.
It will be a messy job.
Grip-tape from 3M, sold
at Ace Hardware
as "Stair tread" material is available in different widths at whatever length you require.
It will be a lot easier.