So no processing and no sugar. Simply fridge storage for a week? Most, not all, of the approved NCHFP and Ball recipes for pickling fruits call for a higher ratio of vinegar to water. I think I would use the NCHFP recipes for Watermelon Rind Pickles instead subbing the grapes for the rind. The seasonings and amount of sugar in that recipe are optional IF you just want limited fridge storage. If you want shelf or longer storage you'd want to include some of the sugar and process them in a BWB as instructed.

Otherwise yours is an untested recipe so done-at-your-own-risk.

Dave

http://nchfp.uga.edu/how/can_06/watermelon_rind.html