Support for searching using `lat` `lon` instead of `zipcode`?

For whatever reason, CG does not deal with my [large TX] zipcode well. So on CG I always use the "use map" option in my searches. That replaces `zipcode` with `lat` and `lon` params.

But I'm getting:

```
'lat' is not a valid filter
'lon' is not a valid filter
```