Looks really good but a few things for you to think about. Anything I do with a plasma cut is coarse at best. My suggestion would be to make all the big cuts on the large power shear at work, then take it over to brake and make any edge bends you may have. I see you have a slot right where a seat cutout may need to be. I think for the slots unless you can get the shop to mill them out for you your next best bet would be to drill a hole on each end and connect with a sabre saw, and then some hand work with a file to knock the edges off. Maybe a few larger holes with a hole saw. The one I have now is longer and narrower than any I have had in the past and it seems to work really well, I don't seem to catch my leg on it at all.
I actually like this one so much I will either buy it to modify it for the Husky or see if he work with me to modify it, the Husky has a long tail so this should work reasonably well.