i`m lucky we have are own septic tank thats over 100ft lower than the toilet and although we are on mains water we also have a dammed spring that feeds the cows with water thats got a 200ft head so plenty of pressure and i recently installed a tap system so my water can be changed too spring water quickly!
if i had too use a system that was reliant on the sewerage i think the best method would be to divert the soil pipe into a container or a pit dug in your garden,them compost the waste! you could dig a outside toilet but its much nicer too do your business in your home and flush it