I would definitely go for some sort of CF and Kevlar sandwich when trying to reinforce such a "through hole" i Glassfibre..
Also try to build up a suitable "radius" using som filler, or just winding some CF tow around the "hole" the build up a radius from the flat deck up the side of the tube going through.
If you sand down the glassfibre and clean and degrease it thoroughly, the epoxy will bind to it very well, especially if the styrene has had time to completely evaporate from the GF.
If you as you describe, have cracks "radiating" out from the hole, then you will need to let the new reinforcement go some distance past the ends of the longest cracks. It then becomes a matter of taste (look of the repair) and economy ... (cost of CF /kevlar)
If I were to do this I would buy enough Carbon Kevlar crossweave to do a proper job
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