Just came to my mind.
If you auto connect to WLAN, and set a search interval i would think that WLAN is enabled every ... lets say 30 minutes.
If you can bind a WLAN to a cell ID it could keep WLAN disabled if you are in no cell a WLAN should be in.

So it would be like:

1. connect to WLAN
2. save actual cell ID to this WLAN
...
1a: search interval of 30 minutes reached
2a: is actual cell ID saved in any known WLANs?
3a no: do nothing
3a yes: switch on WLAN and try to connect

Hope it is understandable. Dont know if its doable at all (CSSU?)

This is not doable as a lot of wifi bits are closed, and doing yet another daemon is just a workaround

It is doable :-)

You could hack together a script or two capable of doing this for you. Here is a python script that will output the cell ID, run this periodically and use the returned value to turn on your WiFi if it matches some predetermined ID.

Keep in mind that pretty much every cell you can access is going to be bigger (in some cases much bigger) than the footprint of your AP, also you may not always be handed off to the same cell in any given location so you'll need to fudge things a bit to get it to work.