Never under estimate the power of pony pipe clamps. I have usedthem for structural framing of wood and metal system, boatbuilding, cabinet making, bike building...you name it.
the a frame is the standard 2 legs for the sides the 1400lbs load was a concern so I ran an additional down leg. There are 3 horizontal angles 1 10" down from the top to support the triple 2x6 beam. I nailed 2 beams together to make them lighter and more portable. The third beam is clamped to them. 2 clamps are used on each end of the beam. 2' down from that angle is another, I put it there for more angle support for the beam... I was a bit concerned about the load on the beam. The final angle is at ground level. All this is further supported by a kicker which was clamped to a center legthan run to a 14 GA angle which was attached with lead shields to my driveway. The a frame made not a sound when under load. Solid as a rock.only a very final amount of vertical deflection on the beam. And the pieces easily store away.
Rich