Last time I filled my boat with 50 gallons of fuel, it took over 30 minutes and had a lot of back flow.
(Warning -- do not operate electric equipments inside gas stations, or when fuel vapors are present!)
So I decided to take my cheap portable leaf blower to the dock, remove the blower pipe, wrap the air outlet with a towel and point it at the gas filler port. After a few blows, water was coming out of the fuel vent, and I could hear gurgling sounds inside the fuel vent.
When water stopped coming out, I tried filling the boat with a portable 5 gal tank. Again, I could hear gurgling sounds inside the fuel vent, indicating that air was vented out while fuel was going in.
The fuel vent is supposed to have a "gooseneck" to prevent water from flowing inside. However, the one on the R200 is tiny, so water probably flowed in there easily and pooled up to block the air vent passage.
Instead of using an electric blower, I think it would be much safer to:
(1) Use a foot pump https://www.amazon.com/Airhead-AHP-F1-AIRHEAD-Foot-Pump/dp/B000FE9CGE/
(2) Unscrew the fuel vent cap and suck the water out using a syringe https://www.amazon.com/Carejoy-Indutrial-Syringes-Scientific-Injecting/dp/B07DXS7ZTV/
The latter is probably more effective in removing all the water but requires more work.