This product is not intended to replace a conventional toilet in this scenario. It uses only about a pint of water per flush and thus has a very limited flushing distance (20 FT max). Also, it does not have a water trap like a conventional toilet -- instead it uses a mechanical trap (a ball valve). This means that if it breaks it could allow sewer gas from the septic/ holding tank to come back into the building, creating an unsafe environment.

It can, however, be used in conjunction with a Sun-Mar central composter (e.g. Centrex 2000). This would allow for the "black water" or toilet waste to be flushed into the composter and be recycled. This in turn would drastically decrease water usage, lessen the burden on the septic/ holding tank and decrease the frequency of pump-outs.
This can be done to effectively relegate the septic to gray water handling only, which will dramatically increase the water quality moving through the septic and into the watershed (decreased faecal coliform count, decreased suspended solids and decreased biological oxygen demand).