The South African domestic biogas industry has been inhibited by a dearth of domestically available technologies suited for local conditions and needs. Contemporary research suggests that Chinese Fixed Dome Digesters (CFDD) could perform adequately within South African, rural, conditions, because of their relatively long lifespan, ease of operation and low maintenance requirements. However, in rural communities, where the majority of decentralised biogas interventions occur, digesters tend to operate at long HRTs and with low influent TS content, due to limited mixing and a lack of additional heating. These conditions limit the organic loading rate of these digesters, and as such, are prone to overloading, uneven biogas production, or system failure. The purpose of this paper is to build on contemporary optimisations of the CFDD design, to contribute to the development of an optimised small scale digester design for rural South African areas. The investigation tested a prototype digester with two experimental design features; orifices designed to create partial retention of feedstock before it enters the digester’s active volume and baffle arrangements designed to enable self-mixing, were tested in continuous operation in comparison to a control. Overall, the optimised digested produced 9.3 Nl/KgVS (approximately 10%) more biomethane than the control. In addition, the digester was designed as one unit which eases fabrication, transport and assembly, and material and structural design aspects were investigated as part of the optimisation. Furthermore, an assisted controlled heating system has also been designed and proposed especially for colder climates regions South Africa. This design has specific relevance within the South African biogas context, as well as within other Global South and sub-tropical markets.