I ride those roads on a regular basis. Your proposed route would work fine. When I use Genesee I take it to La Jolla Village Drive/Miramar Rd and then head east on Miramar. Or, I stay on Genesee down to Nobel and take Nobel east to where it joins up with Miramar east of the 805. That is much nicer riding than along the busy Miramar road.
You can also ride directly thru campus from the intersection of Torrey Pines & Genesee - there is a bike path on the SE corner that connects with Voight Rd that takes you directly across campus to connect with Genesee at Eastgate Mall. That route avoids the sharp steep drop down to I-5 and the climb back up on Genesee. It is good fast two lane road that is much easier than Genesee.
If you don't want to ride along Miramar Road east of the 805 (good shoulders but rough and a lot of traffic and a lot of glass and debris) you can turn N on Camino Santa Fe - then Trade St then Arjons Dr then Mirafani Dr and end up south on Camino Ruiz for a block- then east on Activity Rd and eventually on to Kearney Villa Rd - there is almost no traffic back in the business park.
It is a pretty nice and easy ride from Gillespie thru Mission Trails Park and down to Old Town - almost all downhill.
I ride from Harbor Island to Santee/Lakeside and La Jolla/Miramar/Pomerado/Scripps Ranch via Kearney Villa and/or Santo/52 or Mission Gorge almost every week so send me an e-mail if you have any more questions.
I can send you a .kml file of any or all of the routes I describe.