As the resident Sound Destroyer on this board I feel compelled to add to this thread.
Firstly, if you want insights and approaches into the not-so-ordinary stuff, I'd higly recommend you read RachMiel's columns in the Computer Music magazine. I know of him from the Native Instruments Reaktor forums where he contributes with many outstanding and out-of-this world Reaktor instruments that definitely push the boundaries of audio imagination. His columns in the Computer Music magazine are great as he goes into great lengths regarding music composition, incorporating classic ideas that have reached us from as far back as Baroque music into modern ways of doing things, and quite a bit of sound mangling ideas.
Due to the highly experimental nature of what you're doing, it would be difficult to give ideas as to mic placement and other things for having 50-100 layers of guitar drone... heck, you could even take a small electric fan, and use that to "strum" your strings. While you're doing that, why not stand right infront of the amp to even generate some feedback through your pickups? That might or might not some useful elements to your layers
The people that suggested that it is likely that the result will be just a mess are right. However, it could be a mess that's highly useful in the right context.
Aside from your mic technique and gain staging, it will also be important to figure out what notes you play. You might for example play some low notes with less distortion and some high notes with more distortion, thus creating some interesting chordal sonorities that might not be possible otherwise.
Other than this, some post-processing might add some useful touches. For example, you could use some filter plugin in your DAW and do filter sweeps using LFOs that are sync'd to the tempo. You might even do this to several tracks each with it's own filter that's being swept by a different filter (low-pass, band-pass, notch, phaser, high-pass... etc), using different frequencies for LFOs to make a nice, living-breathing organic stuff.
While having 50 layers of guitar while you're playing the same thing (or close to it) might be useful, it might be more useful if each track was doing something different.
Finally, listen to acoustic/orchestral works from 1960's by peopls such as Krzysztof Penderecki (for example his Threnody to the Victims of Hiroshima), Luciano Berio, Iannis Xenakis to see how these guys achieved some far-out textures with nothing but a string orchestra by having each player in the orchestra play something different, microtuning and such. This will definitely expand your horizons and give you some ideas to try out in a home studio environment to boot. If you can read music scores, even better. Follow the score of Threnody to the Victims of Hiroshima with the score and it will make your jaw drop.
Finally, a drone is not just a drone. It supposed to immerse the listener into a world, it shouldn't be static (unless you intend to turn your listener into a Zen Master
) Figure out ways to give it life.
Experiment, experiment, experiment.