1990 Hydra Sports Repair

[Fish1234]

First time poster with a non Sea Craft. I am filling large holes/openings up to 8"x30" on a 1990 Hydra Sports console. I do not want to paint so I am using gel coat. I will only bed plywood where the controls and sea star steering attach.

I have ground bevels and intend to:
Wax MDF and attach it to the outside of the holes/openings
Spray gel coat and Dura Tec
Apply 1.5 oz mat
Polyester resin with cabosil
1/2" marine plywood
2 layers of 1708

Please let me know where I am wrong and what ratio should I mix the gel coat and Dura Tec. I plan to spray with a Harbor Freight HVLP gun with a 1.8 tip.

Thanks in advance. Any advice will be much appreciated. Joel