Very intresting, heres how you do it:
I know this works with the 32 bit build
Extract the LOD 0 texture to the maps folder of the ship you want untextured and make it a .TGA , dont leave the .pcx file in there too.
Create a mission with you and one other ship.
Save it, start FS2 32 bit build with -32bit command line.
Load mission and make sure the ship is there, press escape alt - Tab out of FS2 and delete or move the lod 0 or main LOD .TGA map out of the maps folder.
Restart the mission
When you get close enough to the ship and it shows LOD 0, Viola! you have a very white, untextured ship and one ****load of lag.
Have fun and post pics.