I was in the valley last weekend 7/10-11. I've been meaning for some time to check out Sunnyside Bench trail and see how far up towards Fern Ledge I could get.
I didn't get anywhere near Fern Ledge, in fact I never left Sunnyside Bench trail, but I did get all the way across to the top of Lower Yosemite Fall. As you can see in these videos you can get awfully close, suicidally close I'd say.
To get to the trail I rode the shuttle bus and got off at the Lower Yosemite Fall stop. I started the walk up to the bridge. You get to a junction where left takes you to the Lower Yosemite Falls bridge, and right goes up hill along the Valley Loop trail. I went uphill on the trail passing NPS employee residential housing on the right. You're in forest the entire time. You get past the housing and reach a couple of stock trails "Government Stock Only" heading down to the stables. As you reach the top of the hill and the trail flattens out you'll see the stables downslope on the right. You come out of the forest and have a creek gully and boulder tumble upslope on the left. Head uphill between the creek gully and boulder tumble. You should quickly find a climbers usage trail that'll be pretty clear the whole way across the bench to the top of the falls. I found the trail pretty easy to follow and safe for the most part. If you run into any trails going up stick with the lower one. The trail skirts the cliff face and is fairly exposed in a few places, so be careful and don't slip or else!
Slide Show of Photos
First good spot looking down at the precipice
Another video from the first good spot looking down at the precipice
I managed to work my way up the slabs up the gully to get a better look at the first upstream pool.
A few traverses across the slabs and grass spots took me a bit farther down/closer to the water.
Afterwards I just wanted to cool off. The breeze coming off the lower falls at the bridge was close and seemed like a nice spot. I sat there watching the tourists. Can you see the rope hanging off of Lost Arrow? The railing at Yosemite Point?