Yes, it's possible. I usually do an initial fill through the open thermostat housing, then when the coolant level stabilizes there, install the thermostat and upper radiator hose and continue to fill. Drilling an air vent hole about 1/8" in diameter in the thermostat is also a good idea, and cheap insurance. The water pump impeller MUST be submerged to move any coolant- - - -it's not a self-priming pump.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!