Use Marris Otter w/ some carapils, and caramunich. Use Extra light dme to get to gravity for your IIPA. Load w/ hops, namely late and dry hop.
Use same base, but add black malt and chocolate. Use Extra light dme to get to gravity for your RIS. Load w/ hops, namely boil and flavor.
I'd rather have a bottle in front of me than a frontal lobotomy.