I beg to differ on both counts.

All it takes is a gentle glide at less than 1/4 tank ( somewhat similiar to what he is experiencing ) to cause this to occur as he describes.

You can do this for quite a while, especially when there is a headwind and you are coming down from high altitude....

Or worst still coming out of a blender type move into a gentle glide ( tore up a plane last weekend with just this move, when the engine died due to fuel starvation... ).

Adding a loop doesn't help much. It does delay the time before the "bubble" or air hits the carb, but when it does the motor can and will still cut out as I painfully experienced... yup I had a nice loop in the lines.

What does help is any measure that can be undertaken to keep the clunk in the fuel as long as possible especially when there is less than 1/3-1/4 of fuel in the tank.

If the fuel tubing can bend downward a bit w/o kinking, the problem is ameliorated to an extent ( or rather it's delayed until the tank is even more empty ). Even turning the tubing so the "natural" bend of the tubing faces downward helps this a bit too... that is unless the plane is inverted.

A header tank may help him to be able to run the engine until the main tank is almost completely empty... so that is not a bad suggestion, although it adds a bit of complexity and weight to his setup.

Or he can just time his runs to prohibit running the fuel so low... or do the same and install a bigger tank.

As MiniFlyer says "You're flying too long and running too low on fuel. "