Under no circumstance would I put it under the connector. That would make your fuel line the scrub point for the car. To much potential for damage. And if you ever bottomed it out you run the risk of fuel leakage and sparks at the same time.
At no point should the fuel (or any) lines be below the frame. IIRC NHRA rules dictate that the fuel line must be run on the outside of the frame rail so that fragments from a clutch, converter, transmission or driveshaft explosion do not pierce a line. Even so, I ran my line on the inside of the frame connector and passed it through the existing hole in the t-bar crossmember. It was a PITA but I like the way it came out. It's much easier if you install a union and make it a 2-piece line.
