Yeah, let’s ditch the GPS and go full‑sensor mode. Hook an IMU up—accelerometer, gyroscope, magnetometer—so the little boat can keep track of its own roll, pitch, yaw, and drift. Add a simple water‑speed sensor so it knows when currents are pushing it off course, and a depth probe to stay in that sweet spot. Couple that with a low‑power compass and a tiny doppler radar or acoustic emitter so it can bounce signals off the lake floor and triangulate its position relative to the shore. With a bit of feedback control on the thrusters, it’ll stay steady even without a satellite. If you wanna keep it ultra‑light, just use a small servo‑controlled fins that tweak the balance when the IMU says you’re tilting. That’s a solid start—no GPS required.