That's a very doable drive, I've done it from Yosemite to SD once before.

My wife and I spent 2 or 3 nights in Yosemite last May (the week before Memorial Day). Based on that experience (and the dozen or so other times I've visited) I'll mention a few things.

The Mariposa Grove is the stand of Giant Sequoias off CA 41 (the south entrance). It has been closed since July of 2015 for renovations/restoration. It will NOT be open when you visit. (We choose to go back to Yosemite in August because the official story was that it would reopen this summer. Now they've changed that to the fall. DOH!!!

) I know that Sequoia National Park is some miles off to your right (going up). I've never been there and believe you really won't have time to swing over.

Glacier Point might not be open. During our visit last year it was sometimes open in the afternoon and never in the morning. The roads would refreeze overnight (it's 3000+ feet higher than the valley floor) and might not be passable all day. I hope things are better for your visit.

I believe you'll be spending Wednesday, Thursday, and Friday nights in the park. I've never camped there (although I've stayed in the Curry Village permanent tents several times). About half of the campgrounds require reservations and the rest are first come (but supposedly fill up by noon). You need to get on the stick about reservations immediately (and it is absolutely too late for most if not all places in the valley floor). I don't know about camping outside the park.

If your heart is really set on seeing big trees you might check out Calaveras Big Trees State Park. That's about an 8 hour drive from San Diego and lies northwest of Yosemite. I've been, it's very nice. Columbia State Historic Park (think old west gold rush town) is between there and Yosemite; I recommend it too.

It's definitely possible to see a lot of Yosemite as a day trip (done that too) if you can't get reservations there. Should you decide to visit Calveras SP and/or Columbia SHP you could spend Wednesday night somewhere around there (Murphys is near Calveras and has several wineries if that's your thing), visit one or both of the state parks Thursday, spend Thursday night as close to Yosemite as you can (I've spent nights at Hotel Charlotte in Groveland twice), spend all day Friday in Yosemite, spend Friday night somewhere outside again (El Portal? Fish Camp?), and then head back to SD Saturday.

Yosemite has a great (and free) bus service in the Valley Floor. Buses run about every 15 minutes and continuously drive the loop. Yosemite Falls is an easy walk from a bus stop. Yosemite Chapel is picturesque. There may (or may not) be tubing available on the Merced River. The view of Half Dome from Sentinel Bridge (and lots of other places) is cool. You can walk to Mirror Lake from a bus stop. You can walk to the Vernal Falls footbridge (tiring for us older folks) and if you've got the legs for it continue up the Mist Trail from there to the top of Vernal Falls. Check out Yosemite Hikes for lots of information. Places you can (should) visit that aren't in the bus loop are Glacier Point (if open), Tunnel View, Bridalveil Fall, and the Gates of the Valley.

Seriously, if you can't get reservations in/near the Valley Floor you really can see a lot just visiting for a day. Just be sure to get there early as the parking (all still free as of last year) fills up early. Have fun!