SW sheet metal will not be able to make a flatenable model of these types of part without additional add-in(s). there are sections that are a) not constant thisckness and b) that are stretched and formed. SW only really handles bends.
but you should not care about the flat, since you would never see that version of the part.
If you are going to be using it in assemblies, you'd be better off just making it a cylindrical solid with some tabs added. Trying to fully model it with true thickness and everything is just going to slow down your assemblies and use up resources that could be better used elsewhere.
Of course, if you just want to do it for the fun of it, then by all means, go right ahead!
I think that's the way I'll go with maybe a revolved "bannana jack" type end on it. It would be nice to be able to model it up correctly should someone ask however. There's a lot of things that would be nice to do, but I'm still climbing the learning curve.