You are venturing into uncharted territory my friend. I don't think anyone here has done those things while fasting before.
The most natural is H2O2. Peroxide is found naturally in all water exposed to air in trace amounts. As long as you don't go overboard I don't think that it would really be contraindicated.
As mentioned earlier, Shelton was against enemas but there are people that do it.
I would be hesitant to use charcoal without fiber to move it through.