not sure how the cost adds up compared to the other things you've listed, but i've had good luck with using disposable baby diapers. i guess using a cloth diaper would be cheaper in the long run if you take propper care of it.
i use his method to stuff depends with pampers size six baby diapers. lasts 2-3 times longer than a depends diaper alone. really swells up, which i like.
for me, its an issue of timing. i normally poop at work, right after lunch. i normally wear diapers in the evenings, after work. in other words, i'm never able to be diapered so that nature can take its course. hence the substitutes.
i find instant mashed potatoes work well for fake messes. oatmeal always sticks to the side of the bowl and i have trouble getting it into the back of my diaper.