Would you keep the spare tire on? The sharp angle design would probably be worse if you have the spare tire on too.
I would think it would be way better to go with a rounded design, even if it only tapered down a couple of inches (due to the short distance).
Huh, I just had a thought. Is there a way you could keep the frame you already have and just bend the top bar down, cut the back vertical bar to match, then weld them back together? You could even cut all of the bars off from the attaching frame, and weld together a better design all together.
And as far as the soft top goes you could do a tuck on that back part. It would be a simple tuck if you weren't angling in the sides too.
That way you'd have the same ease of taking it off and similar look.
Edit: Thank you Flakbadger for the picture. That's exactly what I was thinking!
Oh, and hey, that little black mark you have going out the back of the design idea gave me another thought. Adding a kammback on the back would probably help too!