Oly Plan/Mary Plan Slight Conflict

So I am using a BT plan for my first Oly on September 7th. I am also planning to train and run the Marine Corps Marathon on October 26th, using Hal Higdon's Novice 1 plan. So I superimposed the two plans last night to make a calendar of the next few months. It works out mostly fine, with the exception of the week of my Oly, where my long weekend run is 16 miles. Obviously, I won't be running 16 miles the day before the Oly, or the day of, or even the day after. I don't think I should skip it altogether, and I don't want to get too far off schedule by bumping it up a few days.

As a reference, the run volume for the week of the Oly and the week after are as follows:

Tues - 3 miles, Wed - 8 miles, Thurs - 4 miles, Long Run - 16 miles (Oly)

Tues - 4 miles, Wed - 8 miles, Thurs - 5 miles, Long Run - 12 miles

The longest run before the 16 miler is 15 miles. And the long run following the 12 miler is 18 miles. Any thoughts on what I might be able to skip/move around, etc? This will be my first marathon, so I want to make sure I follow the training plan as much as humanly possible, as that's what seemed to work for the 10-Miler training that I did awhile back. This also means not doing a smaller tri I was going to end the season with in very early October as it conflicts with the 20-miler of my plan, the longest run, which I obviously cannot skip.