Cross-feeding fuel ruins flight balance in planes

[colmo]

I\'m trying to build a much bigger tri-engine version of my biplane but have hit a snag regarding imbalanced fuel use.

First of all, the struts and wings were diverting fuel from the central tanks to the two peripheral ones, which did not need it as they have tanks of their own. I disabled flow in the central tank to stop that using the right-click method, before take-off. Is there any way to set this permanently, instead of doing it every flight?

Secondly, I noticed that the tanks drain from the back forward. This means the plane gets very nose-heavy when fuel starts to run lower. Is there any way to make an engine drain all the tanks in their stack equally, instead of one at a time?

Edit: I figured out a kludgey fix - if I insert something without fuel cross-feed between the first and second tanks on the wings, and cross-feed fuel from the now-isolate rear wing tanks to the rear centre fuel tank, all six tanks drain at the same time. Unfortunately, this means inserting an unnecessary item (I used MechJeb\'s decoupler) between the wing tanks.

[Trekkin]

You\'ve hit upon the only really reliable way of doing it. Yes, the serial tank drain is a problem, but apparently doing it any other way requires the implementation of a more sophisticated system of part tracking, which is, as I recall, to be developed. Until then, isolating and connecting all the tanks with fuel lines is really the only way to control how they drain outside of the default.

[colmo]

I can think of one way of modding our way around this - a simple disc of nearly or actual infinite thinness and strength, the diameter of MkI fuselage, nodes on either side, and no cross-feed capability. It would not impact aerodynamics, weight balance or strength, and would simply require additional fuel hoses.