I always ferment on the pulp I use 2kg per gallon, rhubarb is probably my favourite wine.
I've just picked a few kg today as its growing like crazy so I will get some on soon, and maybe try another sparkling version.
my recipe.
Rhubarb wine
2kg of rhubarb chopped into 1 inch chunks and put in a pan with 100ml of water and 100g of sugar, heat and stir until rhubarb is softening and starting to break apart, chuck into FV with 4L of water with crushed campden tab and the juice of a lemon or two, add 1tsp pectolase, stir well and leave overnight and next day boil 1L water and melt 800g sugar add to FV, add more to hit your preferred OG (I aim for OG around 1075 -1080 but add more sugar if you like stronger wine)add 1 tsp yeast, 1tsp yeast nutrient, leave to ferment for a week stirring daily, sieve/strain off pulp into a clean dj and leave to finish fermenting and clearing.
rhubarb ice cream is wicked too!