We're trying to get the CurrentPage in a Surface Controller in v6.1.5 when the Surface controller is posted via ajax (not from a begin form request).

our ajax call looks like this:

        $.ajax({
            url:"/umbraco/surface/searchresults/changepage",
            type: "POST",
            cache: false,
            data: $(this).serialize(),
            xhrFields: {
                withCredentials: true
            },
            success: function (data) {
                $(".productListings").empty().append(data);
            }
        });

The page posts to the surface controller fine and the model posted is parsed correctly, but we can't access the CurrentPage model.
We've tried several methods to get the CurrentPage but haven't found one that works.  We're currently posting the uformpostroutevals with the form, but don't know how to force the CurrentPage to be set (the UmbracoContext.Current.PageId is null).

Is it possible to use an ajax post and still maintain the UmbracoContext.Current properties?