I have been recommended the papain powder orally to digest eggs that are being swallowed from the lungs. In my experience it works well in the upper colon, and as most meds it does not reach the lower colon. Cranberry juice works well flushing out bacterias that are continously being carried back into the intestines by the worms themselves or being released when they die.
Yes it is certainly true you need to change your plan periodically to get rid of them successfully, as they adapt quickly. And certainly the best way is to find what works well for you.
The mebendazole dose for the enema is in the kalcker protocol. But i think you can just improvise, after all it is only the lower colon area. You can try the horse paste ivermectin, 200ucg/kg (this is a standard dose). If you have difficulties finding mebendazole you can try fenben, the safeguard liquid for cattle. It works well with roundworms and sometimes with some flukes. Many roundworms also birth in the lower colon, which can be controlled by a standard dose of ivermectin orally at 6am. Ivermectin does reach the lower colon. Ivermectin enemas have been used in researches too.