A comment on traffic and crowds.
I spend most of my time in Ewe-Stun nowadays. That has taught me that Anchorage and Alaska do not have traffic. Not even on Gambell street at 4:45 in the afternoon, not on Seward Highway northbound at 7:45 a.m., and not on Seward Highway Southbound Friday evening at 5:30 p.m.....nor at Glitter Gulch on a mid-summer weekend.
...but those times listed are the only times that "traffic" increases in Alaska, IMNSHO.
As noted above, avoid the cruise ship ports....or alternatively, if you would be there anyway, look up the cruise ship arrival/departure times. Hunker down in your RV until there's a window without a cruise ship. If you're going to be in SE AK, there are several marine sights that should be seen and are worth a bit of planning/crowd-putting-up-with.
Don't do Seward on July 4. Don't make your trip to the Kenai Peninsula on a summer weekend...make the trip (coming or going) on a Tue-Wed-Thur instead.
Another thought but with acknowledged bias: My first trip to McKinley (yes I'm an unrepentant namer) was in 1966(?) as a kid when you could fly into the park area. Based on that, I find what's happened at Glitter Gulch to be largely disgusting and offensive. To avoid those crowds, save the $$ on other parts of the trip, park in Cantwell, Healy, or even Squarebanks and take an air charter to fly over Mighty Mac and the rest of the sights in the park area.