Here's my proposed route so far... athough subject to alteration and change due to weather..

Cedar Grove Park, Tustin Ranch
Lower Peters Canyon to Lemon Heights
Lemon Heights to Skyline (yes we are climbing but its early when its cool)
Skyline to Cowan Heights to Newport Blvd.
Newport Blvd to Santiago Canyon.
Santiago to Jamboree
Jamboree to Portola
Portola to Hick's Haul bike trail
Take the East trail back to Portola
Portola to Jeffrey (need to check status of Jeffrey due to construction)
Jeffrey South (again depends on construction) to San Diego Creek trail
SD creek trail to Back Bay East to PCH
PCH to Santa Ana bike trail
SA bike trail to Orange and then find a way back to Tustin.

I think its about 50 miles. If not we can cruise back up Pioneer and Jamboree to add mileage.