There are a few campsites in the town, the state park campgrounds are within walking distence of town, are 20$ a night.
There is another site in town, I think called Idylwild Park? Also 20$, and the sites are a little better than in the state park, but not within walking distence of downtown. They have showers which your lady will enjoy.
If you are heading to the 10 from the town of Idylwild, there is a bundle of campsite areas a few miles past the town of Pine Cove, on your right. These are much better IMO. Stone Creek, is open year round, I think sites are 12$. I believe the 3 other sites, fern basin, dark canyon, and marion mountain open around may 15 usually.
Furthur past those sites if heading towards the 10 from Idylwild, you will see Black Mountain Road on the right. There is Boulder Basin, a bunch of "yellow post" sites (primitive camp sites). The best yellow post site is at the top of the hill at the fuller ridge trailhead, but that road is closed until the end of may.
Usually if we are car camping up there we have a spot for solitude. If heading from the town of Idylwild towards the 10, you will see a Shell gas station on the left in the town of pine cove. If you follow this road (Bee Canyon OHV area) down, down, down with your off road truck you will come to two yellow post sites. No one is ever there. Beware creepy flying demon beeping noises coming from the woods! North Fork San Jacinto River crosses this road right after the sites when heading down, and makes for a real nice chill spot. You might have to share it with some beer drinking off-road enthusiasts, but that never bothered me one bit :)
Also toward lake Hemet, is Hurkey Creek, and more yellow post sites by Thomas Mountain. Also camp areas at Pinyon Pines more toward Palm Springs. I have never been to these campsites.