Nope not a dumb question. A clunk is not used with a bladder, the principle precludes the need for a swinging pickup. A dip tube might be used with larger bladders in case they fold forward and trap fuel. With the large neck diameter and small capacity of balloon tanks, I don't think a dip tube is necessary. In theory it isn't because you are aiming for a void free fill. First - with the pickup of the tank at the top, which is usually nose up - you suck out the air which floats to the top of the fueler, then you fill the bladder* with air free fuel from the bottom, stopping before you fire air into the bladder. Then if you are really diligent, you tap and shake the fuel lines/nose of the model, then draw a little fuel back to suck out any stubborn air bubbles. Then connect to the engine.
* not to be confused with a pressure bladder = inflated tubing