Bubbles in the fuel are most often caused by excessive engine vibration. You may have a propeller out of balance, or rare cases, a bent crank. If this is the case, a bubble-less tank will not help much. You may also have an air leak under your carb or backplate.
I've never had an issue with regular 2 line fuel tanks when the fuel tank is padded and the prop was reasonably balanced. Your problem may disappear with an inexpensive new prop.