. . . . Maybe Frank B can offer some suggestions. Hint, Hint 
. . . .
I thought I did that in about the second post in this thread. Anyway, let's try again.
I've never been to Truckhaven, so can't help with that. I've never done the Calcite Mine Trail, but from what I understand it can change a lot from season to season. As I mentioned in my earlier post in this thread, call the State Park Rangers and ask about any particular trails. They also have a board just inside the door of the Visitor Center that they update regularly. If you don't have a paper map of the area, get one. See the Xcursion Guidelines thread for suggestions for maps and guidebooks.
The 2WD-friendly routes I mentioned in my earlier post were more the kinds of places where the OP could go by himself if no one else wanted to go. That is not to say they would not be fun for a group though. If you're going to have some 4WD trucks along for the ride, and don't mind taking a chance on getting stuck, there are a few more options that I can think of.
Fish Creek and Sandstone Canyon (at least to the first rockfall bypass): I know of several 2WD's that have done this all the way out and back with no problems. This 13.5 mile each way drive is considered one of the most scenic in Anza Borrego. The Park rangers suggest 4WD for the portion from the Wind Caves parking area on, and if you're not careful or don't know how to drive in sand you could have a problem, but then you'll have your shovel, or better yet friends with tow straps. Don't miss the hike to the Wind Caves at about the 4 mile point from the trail start at the mouth of Fish Creek (at the end of Split Mountain Road). Also, unless you want to spend some time on a strap, and have friends with patience, you might want to avoid Loop Wash. That said, I did follow a Honda Element (probably the AWD version) through Loop Wash once (and didn't see any pieces left behind), and we had a 2WD drive with us the last time we did that as a club run. He did smack the front end pretty hard on a few rocks in order to get over them though.
Rockhouse Canyon / Clark Dry Lake: There is a 10-mile or so each way road that runs up the side of the dry lakebed, by the old WW2 Navy bombing target and emergency airstrip, and heads up toward Rockhouse Canyon past the quarry. You can find it on a map at the point a little before S-22 turns straight south right near where it intersects Henderson Canyon.
Do not drive onto the dry lake bed, stay on the trail. It's scenic up there. This is an out and back the same way drive, you'll know when to turn around (or you'll get stuck in some rocks if you don't pay attention to the change in trail conditions in time).
Fonts Point: Again, the rangers recommend 4WD but I see all sorts of vehicles at the parking area for the view point. One ranger told me it was the most popular spot in the Park to get stuck in the sand. The amount of sand varies from season to season, I've not been there since Spring, when it was pretty hard packed. If what I saw last weekend in Inspiration Wash was any indication, it might be a lot softer now. Still, if one does not drive like an idiot, and maybe have a 4WD friend along, it should be fine.
Military Wash (and probably Fault Wash) going north from San Felipe Wash at the edge of the Ocotillo Wells OHV area would be okay probably in 2WD. Every time I've traveled Military Wash it's been pretty hard packed, no problem at all in 2WD. There are also a bunch of the wider dirt roads in the OHV that should be fine, and I've seen lots of what look like 2WD trucks out in San Felipe Wash in the State Park side going all the way west to Borrego Springs Road I would think.
Hope this helps, this is what I can think of right now. Feel free to ask anything specific any time.
