looking at the pic where you have the bar held up...I'm thinking that the simple solution is to make four new splice plates (that triangle shaped piece) that are taller and double them up front and rear of each bar to give it even support (now that it's not sitting on the lower upright). That shouldn't be expensive. It might not be just a simple triangle anymore (to avoid too large of a triangle that gets in the way) ... but, easy peasy.