A key component of increasing energy access globally is providing rural electrification using off-grid minigrids. Minigrid developers have specific design and planning needs including: (i) equipment sizing and resource allocation, (ii) distribution network layout, and (iii) reliability cost-benefit analysis. Optimization of each aspect is necessary to minimize the cost of electricity for the customer and to maintain a target level of reliability. This work presents an extension of an open-source holistic minigrid design and planning toolset called uGrid, created by the minigrid developer OnePower in Lesotho to perform resource allocation and sizing optimization of energy generation infrastructure based on statistical load estimates. The extension is an improved uGrid with advanced dispatch controls and the newly added uGridNet with distribution network design using Gaussian-mean clustering, network reduction, and N-1 line loss reliability cost-benefit analysis to optimize the network topology considering cost and reliability. A case study is performed using the toolset to design a minigrid for the Ha Makebe village in Lesotho, highlighting pole placement capabilities and changes in network layouts over a range of reliability probabilities. Added costs for reliability range from 18% to 130% for reliability probabilities from 10% to 100%, providing developers with a wide range of options to consider. This combined toolset is designed and packaged to meet the engineering design needs of minigrid developers, with the goal of supporting affordable rural electrification and energy access initiatives worldwide.