You could figure the angle you need for a cove cutting JIG, put stops in the right places, lay the board in it at the first stop, turn on the saw, raise the blade a little, push it to the next stop, pull it back, raise the blade a little, push it to the next stop, until you get your required depth. That would work. I wonder if you would get a perfect 90 degree, flat spot for your fingers though? If not, a 90 pound deep would slip out of your hands?