I have a similar commitment. My fitness is also down the john at this time. This is the short version of my sched:
March - short day = one-legged pedaling drills plus easy ride or 15 minute LT intervals; long day = 2-2.5 hrs.
April - short day = 15 minute LT intervals 2 wks, then 10 minute muscle tension intervals 2 wks; long day = 3-3.5 hrs.
May - long and short days = 15 minute LT intervals, long day = 2-2.5 hrs.
June - long and short days = 5 minute high cadence power intervals (over LT), long day = 2-3 hrs.
July - short day = 15 minute LT intervals; long day = 3 minute power intervals, long day = 2-3 hrs.
August - short day = 30 minute LT intervals or 45 second sprint intervals; long day = 3 minute power intervals, long day - 3 hrs.
Except last two weeks before the trip, no intervals or hard riding, and only about 7 hrs/wk total riding.
You can simulate the formal sessions on the long day by using a group ride and attacking or pulling at high speed, about as shown.
On days when you don't ride, if you can get up early and just ride a trainer or rollers for 30 minutes in zone 1 (no need to shower), it will be well worth it.