Here was my old solo seat I was using... I got a universal mount for it that was meant to be bolted around frame tube... I flattened it out and then drilled holes so that it would bolt to where the stock seat bracket (off the gas tank) went:
After I cut the stock rear support brackets, it ended up sitting like this. I did not run springs on it, since I've got the struts on the swingarm still.
Front bracket originally looked like this (the top piece):
Mine was 100% bolt on with no welding required.