You can do a GetCapabilities request, copy the response, and put it in a public web folder, for example, save as MyStaticGCresponseVersionmno.xml
then edit this file and remove the <CRS>CRS:84</CRS>
, any BoundingBox (<BoundingBox CRS="CRS:84"...
), and also change the URL for the GetCapabilities requests (<OnlineResource xlink:type="simple" xlink:href="..."/>
) to the static file location.
Then you can use this 'static' file as the service URL.
That works for most clients, but it will fail a WMS validator.
Alternatively you could use MapServer, and cascade the GeoServer service through it.
For example,
Here is a GeoServer WMS service:
http://13.95.69.121/geoserver/erl/ows?service=WMS&request=GetCapabilities
with
<GetCapabilities>
<Format>text/xml</Format>
<DCPType>
<HTTP>
<Get>
<OnlineResource xlink:type="simple" xlink:href="http://13.95.69.121:80/geoserver/erl/ows?SERVICE=WMS&"/>
</Get>
<Post>
<OnlineResource xlink:type="simple" xlink:href="http://13.95.69.121:80/geoserver/erl/ows?SERVICE=WMS&"/>
</Post>
</HTTP>
</DCPType>
</GetCapabilities>
and ...
in the mineralOccurrenceView layer
<KeywordList>
<Keyword>features</Keyword>
<Keyword>mineraloccurrence</Keyword>
<Keyword>earth resource</Keyword>
<Keyword>mineral resource</Keyword>
<Keyword>mineral occurrence</Keyword>
<Keyword>mineral deposit</Keyword>
<Keyword>mine</Keyword>
</KeywordList>
This service was being used in a portal which uses keywords to trigger functionality. To test the keywords quickly (client developers were not service providers) a static file version of this file was created:
http://ogc.bgs.ac.uk/OWS/GTK.xml
with the OnlineResource changed thus.
<GetCapabilities>
<Format>text/xml</Format>
<DCPType>
<HTTP>
<Get>
<OnlineResource xlink:type="simple" xlink:href="http://ogc.bgs.ac.uk/OWS/GTK.xml"/>
</Get>
</HTTP>
</DCPType>
</GetCapabilities>
Other OnlineResources remain the same (point to the actual service).
but keywords were change for the layer like:
<KeywordList>
<Keyword>features</Keyword>
<Keyword>mineraloccurrence</Keyword>
<Keyword>earth resource</Keyword>
<Keyword>mineral resource</Keyword>
<Keyword>mineral occurrence</Keyword>
<Keyword>mineral deposit</Keyword>
<Keyword>mine</Keyword>
<Keyword>Erml_lite_age_or_litho_queryable</Keyword>
<Keyword>Erml_lite_queryable</Keyword>
<Keyword>Erml_lite_queryable_geoserver</Keyword>
<Keyword>Erml_lite_queryable_geoserver_workspace</Keyword>
<Keyword>Erml_lite_queryable_4</Keyword>
</KeywordList>
The edited content in this case was keywords, not CRS, but the principle is the same.
Now for the client you use the http://ogc.bgs.ac.uk/OWS/GTK.xml
URL as the endpoint instead of the http://13.95.69.121:80/geoserver/erl/ows?
version.