Never made rhubarb pie this way, just always made it DGM's way. Fresh or frozen. Mixed it with flour (or corn starch) and sugar and put it into the pie crust and put a top crust on top. I have always thawed the frozen before baking it because of the water content from being frozen. Top of the crust I always add some a sprinkled sugar, small pats of butter and a little 'cream' or milk on the top to make it brown better. Although, sometimes I cook the rhubarb and mix in the flour and sugar before adding it to the unbaked pie crust to make sure I have enough thicker in the rhubarb. Guess at my old age of seventy two, its likely to remain being made this way. Other ideas sound good if that is the way you like to do it...go for it.