Yeah, when you are putting fuel into the tank you are also forcing fuel into the carb as well....

Your problem is not with the tank but with your plumbing.

First make sure that your vent line is clear and permits good flow. You may have a clogged nipple that is permitting pressure to build up in the tank, forcing fuel out of the tank-to-carb line. Check and clear the nipple at the muffler.

For cowled setups on smaller planes I prefer something like this with a two line setup.



which permits fuel ONLY to flow into the fuel tank during fueling.

BTW: "almost touches the back of the tank" is not a good idea.

During acceleration or uplines the fuel tubing will stretch and you can end up cutting off the flow of fuel to the carb as the clunk hits the back of the tank...
( this was responsible for a very hard to find problem on one of my planes... )

Leave at least 1/3-1/2" from the back of the tank for safety.