Matt,
After the cat 1 cross base plan you will be ready to follow on with the 7-Day Mountain Bike Stage Race – Personal Record Plan.
After TSE take a week off then another week of easy riding for recovery.
The next plan to follow to prep for your 18 hour would be one of the 24 hour solo plans.
24-Hour Solo Mountain Bike – Personal Record Plan
24-Hour Solo Mountain Bike – Finisher Plan
Lynda