Wow. This is fun - designing someone else's vacation.
Next, let me say I'm jealous of folks who can just pop over to the Fort for the weekend like yourself.
Having said that....
If you reserved a Premium I like 900 loop. It's small, has a Comfort Station and bus stop at the loop entrance, and is across the street from the Meadow TP. It is a pet loop and we are non-pet folks but the late night barking dog-type-of-thing has never been an issue for us. 600 is close to Meadow TP yet but has little shade. If you reserved a Full, get 1600. They have sites that bump up to the 1500 Comfort Station so you would be on familiar turf almost.
Schedule wise, I would come in Friday evening, do a quick GAG supper, pizza, or roast hot dogs at the singalong, and do the movie/campfire Friday night. Saturday would be MK day (by boat from the dock) with possibly going back to Fort in the afternoon to swim/nap/relax, then back to MK at night for fireworks, etc. MK is busiest from about lunch to dinner. Up to you if you want to eat CS at MK for lunch or dinner or eat back at Fort if you choose the swim option.
Sunday morning I would pack up and leave the Fort pulling the pup and do DHS. You will FP+ the main rides so no need for rope drop unless you want to. Your Fort parking pass will get you into the DHS lot and you will park with the other oversized vehicles. From there in the evening you can head directly home.
Since you asked, that's how I would do a Fort/weekend/MK-DHS visit.
Bama Ed