openlayers 2 - Creating indoor map in GeoServer?

I'm trying to create an indoor map(from floor plan) in GeoServer and display in via OpenLayers.

The only way that I found is to create a Store in GeoServer(in my case, using ImagePyramid) from georeferenced .tiff, which one has a local bounding box([0, 0, 11, 9] in EPSG:3857, in my case).

It works fine, but is there another way?

I'm looking to custom CRS, but I don't know whether it's worth the effort.