Oh dear.
Clipping tanks also increases dry tank weight. Therefore you don't gain any advantage.
Bp editing percentage doesn't increase dry tank weight as far as I know, you could have 1,000,000t of fuel in a tiny tank that weighs 0.5t when empty.
So your rocket weighs less than it should and thus has more performance than it should.
Blazer has the say on whether this matters for shuttle challenge, but I strongly suspect you should immediately start making a no-exploit version right now.