How about strobes doing interiors or something. Can't add more power. You have to open up
Guy, opening to a wider aperture will give inaccurate LCC results, especially in the case where 2 full values more exposure are necessary.
It's easy enough in the situation you are describing to pop off a portable strobe directly at the plex covering your lens. You'd need to calculate the exposure/distance to the lens of course, but many find this produces great results. If you typically shoot at F11, you'd could repeat this without a lot of fuss.
Like Graham, I shoot the lenscast reference shots most of the time at the end of the sequence of shots for stitching. For outdoor work with light changing or clouds moving quickly across the scene, the frames for stitching need to be shot in a quick sequence for the best results and less post production headaches later on. So, having the LCC shots at the end works best for me.
In the case of long exposures, I actually reverse the process and shoot the lenscast reference shots at the beginning of the shoot, knowing that the potential buildup of noise also does not produce a good LCC file. I get the best results keeping the ISO native to the digital back and keeping the LCC exposure under 1 second. In long exposure situations, the portable strobe method works great too. (Nikon SB-900 or similar)
Lonna