The length is not the problem, it's the pull back. If you have them mounted correctly the pullback lies in a horizontal plane level with the clamp. When I said I had to "make sure the bars were not rotated down", I meant that the bars were not rotated below the level horizontal plane. If they were rotated down they most definately would hit the faux tank. If the bars were straight (no pull back) there would be no issues of this kind. But then they would pull my hands forward into a uncomfortable position.(IMO)
Here are the specs on my bars from Python motosports: 27 1/2" width - 3 3/4" pull back- 140mm center, straight no rise. I believe that, for example, 4gasems flanders bars have around 5" of pull back but are wider at over 30".
I don't know if this explains it very well, or even at all. I will post some pictures with my bars at full lock to further my explanation.