Custom PCB design — solar-powered outdoor IoT sensor node (ESP32-S3 + LoRa + GNSS)

We have a locked hardware architecture and need an experienced freelance electronics engineer to take it to manufacturing-ready PCBs. Components are already chosen — we need schematic capture, 4-layer PCB layout, DFM, and fab-ready outputs. This is not a re-architecture. Primary board: a solar-powered outdoor sensor node — ESP32-S3, 868 MHz LoRa (SX1262), GNSS with PPS timing, analog MEMS-microphone front-end, solar/Li-ion power (MPPT). 4-layer mixed-signal, ~110×70 mm, IP65. Key requirements (please acknowledge in your proposal): Sub-microsecond GNSS-PPS timing path (most critical) LoRa-TX ↔ analog/GNSS EMI isolation SUB-25 µA deep-sleep current Outdoor survivability — TVS/ESD, reverse-polarity, 45C ambient KiCad preferred; all source files delivered (no lock-in). Deliverables: schematic, layout, Gerbers, BOM with alternates, STEP, DFM, 2 review cycles, bring-up notes. Two small optional sensor sub-boards to price separately. Please share relevant work in low-power mixed-signal, sub-GHz RF, and GNSS timing. Full technical pack provided under NDA. Fixed-price quote preferred.