Charlie,
Kevlar on a boat like this will not save you any weight at all, that is not the purpose it is only for impact/abrasion resistance. Kevlar is only lighter than glass if you have very small amounts of resin to fabric (a high kevlar to resin ratio), you can get that without a lot of work like vaccum bagging. A plywood boat is not going to gain any benefit from a kevlar sheathing in terms of weight - best case senario you could save the weight of two boxes of shells or a gallon of gas - not worth it in a trailered boat.
Given that I think you like the idea of kevlar to save weight, I'd reccomend against it. It is a pain, fuzzes up and does not lay smooth like glass, is relatively hard to wet out and cuts hard. used a 5 ounce kevlar from Raka under 5 ounce glass, layed it up wet-on-wet. I am extremely happy with the combo, other than how relatively fragile the glass is compared to the kevlar.
If you want to proced with kevlar, here is what I did.
I don't think I overlaped the kevlar at the keel, but kept it 2" apart, I have a wide center strake (3").
I did not tape the edges fo the hull, withthe idea that two layers is two layers, be it glass tape and glass or kevlar and glass.
I did not bring the kevlar up the hull much beyone 8-10". The kevlar I used was not exactly great to work with and I would NOT try anything fancy with it like doing the inside of a well. You do't need abrasion resistance there, so why fight with it.
On the glass over kevlar, the glass protects the kevlar, which can't be sanded well. You aren't supposed to cut the glass with sandpaper, but everyone does. This isn't a big deal with glass, you just put a layer of epoxy over the cut strands. With kevlar, you have a fuzzy mess to deal with that is hard to get under control, especially with the epoxy isn't fully cured (takes a couple weeks to truely cure).
