Need some Inland Empire route advice

So it's time for our annual visit to the inlaws in Hemet. My husband is forcing me on to a plane this time so no bike. :( Sent an email to my cousin in Orange County, an avid rider, and he suggested a ride out of Hemet before he knew I wasn't bringing my bike. It sounds fun and I would love to give it a try. I have found a place to rent a bike but I'm a little scared of the route and wondering if anyone has ridden that way.

We would be going east, up the mountain to Mountain Center just below Idyllwild then south through Garner Valley (I think) ending up somewhere around Anza then coming back into Hemet through Sage from the south. The whole route is 70 some miles. My real concern is climbing up the mountain. If I had one of my bikes with their mountain gearing I would be all over this ride. But the rental bike would be a compact double with standard road gearing.

On the plus side I've been able to log just over a 1000 miles since the first of the year, have been doing weights at the gym all winter and have lost about 40 pounds. So in theory, I should be as close to a lean(er) meaner mountain climbing machine than I have ever been. :o This ride is just the challenge I need to boost my self esteem. On the other hand, I would hate to have to call my husband to get me up the mountain or worse blow out a knee or something.

So if any of you have ridden out the way, can you tell me about it? Thanks, bikerHen