It is known that, in the upper level camps, LBM are subject to random losses. There is, I believe, a level of LBM that overrides this random loss. The trick is to find this level without getting wiped out.
I have found that 15K LBM and 300 AT on LV6 camps will safely win without losses every time. This has even been used with brand new 0 star generals without losses. I have used this number successfully well over 1000 times without losing a single man. I believe it's safe to say this is a fact.
I am currently working my way up the camp levels to determine a solid level of LBM that override the random loss. I am experimenting with LV7 camps right now. So far, I have yet to lose any men with a force of 25K LBM and 500 AT after 35 attacks. After I get over 200 attacks without a loss, I'll post the results and move on to LV8 camps.