Which parks are you planning to do what days? Thursday is the 5K at Epcot, and that will be wrapped up in plenty of time for you to do a “normal” rope drop. Friday is the 10K, also at Epcot, which will also be wrapped up in plenty of time for a “normal” rope drop. Neither of those will really affect the main roads (the 5K only really affects the Epcot parking lot area, and the 10K doesn’t go too terribly far outside the ticket booths and on the main road–and they sweep aggressively in those areas to have the roads clear for people driving in to make rope drop).
The bigger challenges will be for the half marathon on Saturday and the full marathon on Sunday. That’s where you’ll end up with most of the road closures, and so you may want to think about what parks you are going to on those days.
Now…if you don’t mind a painfully early morning, you can actually be in MK before rope drop for either that Saturday or Sunday if you’re willing to do a bit of cheering for the runners. I’d need to check and see what time I arrived at MK, but I believe I was in there around 5:45 AM, and so there was a great time for pictures and the like. When I’ve done it in the past, they also don’t scan admission media to get in, so while you wouldn’t be able to use FP+ selections (because you didn’t tap in your ticket at the entrance), you can theoretically be in the park that day without a ticket.