MarkT:
One possibility is to go for a LiFePO4 pack instead of LiPo, not as dense an energy store, but vastly
less likely to catch fire. There are charge management chips for LiFePO4 available.I've used an MCP73123 LiFePO4 charger chip together with an TS1935CX5 boost converter for
a similar project, schematic/layout available if you are interested.
Mark, how can I get my hands on these schematic?