So, we've got low compression on both cylinders (152-153 vs 176 PSI), no thermostat, and coolant that has a possible scent of fuel or combustion gases.
Plus elevated coolant temps with fan(s) running, with frequent low coolant levels, and also with the overflow tank frequently being full.
Also, when the engine is put under high load, there's reported fluid dripping from beneath the bike.
The coolant pump bypass doesn't show any fluid leakage. And the oil doesn't show cloudiness from coolant contamination.
On the surface, it does sound somewhat like a bad head gasket or warped cylinder head.
One possibility is the head gasket is leaking at an area where the compression/combustion gases are leaking into the coolant jacket, but not into the lubrication system.
That's one possible explanation of the low cylinder compression readings.
There, the cooling system is getting pressurized by the combustion gases, possibly causing the radiator cap to relieve, and sending coolant down to the overflow tank.
Does the overflow tank area show liquid residue (wet or dry), or is the tank cap popped off?
Because the cooling system may be having gases induced, the engine could be getting overheated due to steam bubbles forming in the water jackets as well.
The thermostat could have been removed to treat the symptom rather than the problem, to try and cool the engine.
The only way to really check or correct this situation is to remove the heads, and check for blown head gaskets or warped heads.
And will probably require removal of the engine.