That's not much information (eg, what are the overheating symptoms -- 5 bars on the gauge or steam coming out both sides of the engine?).
Be that as it may, running with a 5 year old battery ain't a good thing maintenance wise for the heavy current Spyder (2015s didn't get the low current high torque DPS).
So I'm thinking one hot day in AZ you went from freeway speed to stop-and-go in traffic without any cool-off transition. Perhaps the coolant was low. And I'm assuming an F3S is the SE6 transmission. So all the residual heat normally dissipated via high air flow, high engine RPM suddenly went into the coolant in a low air flow, low engine RPM and probably hot road surface environment.
Either then or soon after something failed. Could be a seal on the oil-to-coolant heat exchanger (check oil for contamination). Could be a head gasket (check spark plugs for contamination). Could be a fuel injector failing at low voltage (don't know how to check this). Could be a radiator hose inner-outer wall separation blockage (normally manifested at high RPM but ???). Could be a marginal MAPTS or more likely CPS. Could be a solenoid seal or valve failed in the HCM resulting in heat generating clutch drag at idle RPM when oil pressure is low (perhaps using Motul 7100 15W-50 will help).
In summary I think you've managed to damage the tough Rotax 1330. Hopefully the fix is cheap.
BTW the thermostat is integrated into the water pump and everything is plastic.