You should give the epoxy I am using a try. It's a slow cure, 2 to 1 mix and it soaks into the wood better than any I have used before. It is easy to apply with a roller or brush and pretty much self leveling. I was getting those splits too and soaking them with penetrating epoxy, epoxy primer and paint but they came back. They won't with the gel coat. Also, you can sand to a smooth finish and paint directly on it without a primer coat.
MAX GPE just look on eBay for that and they sell quart or gallon kits. I use a scale to measure but the weight isn't the same. The formula I use is I take half of the weight of the resin, it contains the white pigment so it weighs more, then times it by .75 (75%) for the catalyst weight. Otherwise I pour into graduated cups 2 to 1.
GB42-17 Classic Cockpit Model
My personal Banned List; All Polyester resins, Silicone, Bondo and sea sick crew.