As has been said, this would be best discussed on the devel list - however, just for the sake of completeness, there's the long-standing idea to use the original photoscenery patches and turn those into a so called canvas "placement" mode. A canvas in FlightGear is just a placeholder for a property-driven texture (RTT/FBO) - a canvas supports a handful of drawing primitives, which can be organized by grouping them and hiding/showing them as needed, and applying arbitrary transformations and effects.
For such a canvas texture to show up inside FlightGear, so called "placements" are used - under the hood, this works via the equivalent of a texture visitor, to replace a static texture with a dynamically generated.
For the time being, we have placements to map these canvas textures onto aircraft/scenery surfaces, but also to render them inside GUI dialogs and standalone GUI windows (think popups/tooltips).
A dedicated geographic placement would mean that any canvas texture could be applied onto the terrain mesh.
For additional background info, see:
http://wiki.flightgear.org/Canvas_Devel ... y_OverlaysThe reason why I am mentionig this capability is that you mentioned the issue of fetching/caching imagery - and this is something where a canvas based approach could be pretty handy and enormously flexible. For instance, one of the drawing primitives supported by the system is called "Canvas image", which can be used to display raster images - which comes with the capability to dynamically fetch imagery in the background, i.e. automatically:
http://wiki.flightgear.org/Canvas_Snipp ... e_tile_maphttp://wiki.flightgear.org/Canvas_ImageWe also have optional support for a number of web APIs to fetch charts (e.g. OSM), for use in avionics:
http://wiki.flightgear.org/FG1000 Again, all the code is already integrated and working - which is to say that canvas based approach would provide all this for free.
To be on the safe side, it would make sense to discuss your plans with people involved in more or less related efforts (namely Scott/VPB, Thorsten/ALS, Fernando/Compositor)
PS: Whenever people point out distribution issues, the usual idea is using a decentralized torrent based approach.