Generating geo_point based on a couple float

Hi guys,

I need to import a MySQL table into ES where the table has one longitud and one longitud rows. It is pretty much the same use case as the one described in:

so I followed the same steps and I obtained a field:

  "Location": {
    "properties": {
      "lat": {
        "type": "float"
      },
      "lon": {
        "type": "float"
      }
    }
  },

So far so good. Now I'm trying to convert that structure into a geo_point. According to the mentioned post, the solution is to include in the index template:

"mappings": {
"properties": {
"location": {
"type": "geo_point"
}
}
}

Well, I'm driving nuts to try to do it, without success. If I import data and then try to apply the mapping in the console I get an error resource_already_exists_exception and if I define the mapping in the console and then do the import I also get an error (Rejecting mapping update to [gooddriver_positions] as the final mapping would have more than 1 type: [_doc, positions]"}}}}).gooddriver_positions being my table.

I guess I should tell ES that the mapping is meant to be applied just to that field and to use the defaults for the others but I do not find the way to do it.
Can somebody give me a hand and tell me the steps I should follow?

Thanks in anticipation,

Claudio