Are you traveling through the night? Since you first posted your schedule I can't help but think, based solely on my own tub of course, that Rock Hall to Delaware City or Reedy Point in one day (assuming daylight travel) is aggressive. It took someone I know with an IP35 8 hours to get to the Sassafras from RH.
We sail that distance to the Sassarass many times for a just a weekend from Rock Creek to Anchor in Betterton or Turner Creek on the Sassafrass. It's only 25 miles. If we leave our slip by 10 we are usually swimming or dinghy riding by 3:30. We like going north to Worton, Still Pond, and Sassfrass as you can swim in nettle free water all summer. It's a 5 hour trip to Sassafrass, 4.25to Still Pond, 3.75 to Worton in normal stailing conditions making 5 knots. IP are slow sailing boats, but even 8 hours seems extra slow. Your boat isnt a slug and would have no problem doing it in 5-6 hours.
You must be aggressive when dealing with any trip involving the Delaware to Cape May and set yourself up as best possible for the 5.5 hour assist from the current heading down to Cape May (6.5 hours when heading back from Cape May to the C&D. This way you can take advantage of the current and do it efficiently .
Dave on Auspicious has a formulary for doing it in one shot from Worton which works, but may require overnighting.
Going 55 miles this time of year with 15 hours of light isn't really that aggressive. This really is not a sightseeing trip but one of transit. You keep your speed average at 5 knots by main/ motoring as James suggested.
If you leave Rock Hall at 7 AM you are safely anchored behind Reedy by 6 PM. Next day you leave at 6 AM and re in Cape Mt docked by 2 in the afternoon avoiding the Delaware Bay chop and or thunderstorms. Easy trip this way. Sleeping well, drinking well, no nights.