Just Where was Rhosgobel?

[Valandil]

Rhosgobel - the home of Radagast. Where was it? Precisely?

It seems to have been on the edge of Mirkwood, somewhere on the south of that great forest.

One Tolkien source I just read places it between the Carrock and the Old Forest Road, along the western edge and close to the southern edge. But that location is no place NEAR the southern edge.

Looking at Mirkwood Forest on the maps, I could reasonably guess any of four distinct locations - and that it might be in the proximity of any of these:
1. Directly across from where the Gladden flows into Anduin.
2. On the west side of the narrowest crossing of the Forest - directly across the south edge of Mirkwood's "East Bight".
3. At the point where Mirkwood projects its furthest west in the southern part - placing it extremely close to Dol Guldor.
4. At the southern-most tip of Mirkwood.

Which of these do you favor, and why? Or - what alternatives do you suggest, and why?