Storing GML surface in PostGIS

I'm using PostGIS 2.0.0 and would like to store a GML Surface in a way that allows calculating intersections between that surface and various points and lines. In my case, the Surface will have one PolygonPatch with no interior rings and an exterior ring which may be a LineStringSegment, a Geodesic, an Arc or a Circle. The distances can be in the order of tens to hundreds of miles. I see that PostGIS has CIRCULARSTRING and CURVEPOLYGON, which seem to be a good way of storing an Arc, except that they're not supported by the geography type, only geometry. What would be the best way to store this? (I'm quite new to PostGIS and GIS in general, so it's entirely possible I'm missing something obvious.)