Most of the caches are just off the trails in the forest. The trails, in general, form a grid pattern with trails running north/south and east west. This is not absolutely correct, but it should give you an idea of what it looks like.
By bicycle, and caching alone, I was able to do the Presidential series in about 4 1/2 hours (as I recall) and around 10.5 miles. The new caches would add to that time/distance, of course. The only suggestion I can think of that may help is start at the south end and work north. The park more or less runs up hill from south to north, and if you do as I did, you'll have a long and often sandy uphill ride back to parking at the end of your hunt. You could either park at the south end, work your way north and then return south or park north, go more or less directly to the south end and then work your way back. It's a nice series, actually two series now, but it probably won't work well with the CITO Event. Here's a link to the trail system:
BTW, all caches in both series are south of FM 1488.