RE: gas fuel dot ?
You want no aggravation ? First off, get rid of the Tygon..It needs clamps because it gets hard and will slip off or leak....
There is no need to run big diameter fuel lines on ANY gasser, the hole in the carb that the fuel comes through is less than .060 diameter...
Molded neoprene (Hayes Products) is the best, about 1/16 ID...
One line from the clunk to the carb, one line from the vent in the tank coming out the bottom of the fuselage...
A "T" fitting in the line between the tank and carb..You can solder one together easily in a few minutes with some leftover brass tubing, diameter doesn't matter, 1/16 ID is fine...
Something to plug the "T" when flying, commonly called a fuel dot...The brand doesn't matter as long as it plugs the line from the "T"....
The neoprene is perfect for gas...I use it in my test stand fuel tank...It's immersed in gas 24/7 for months without needing replacement...
I run 150cc 3Ws on the stand all the time..The line from the tank to the carb is about 18 inches long...ZERO problems with fuel flow....
Inverted flying will plug the vent and cause siphoning ? You could fly upside down for 5 minutes with no problems there, as soon as the plane is righted the vent is uncovered and more air comes in...The pump in the carb will suck enough fuel to partly collapse the tank, no problem there either...