rear frame question

my question is, what does the frame behind the notch do? in a bagged vehicle with a forward 4 link, there are no suspension supports behind the rear end. is it there for the bed to bolt to? would there be any negative ramifications to cutting off my frame/bed directly in front of the axle and just running a forward triangulated 4 link?

That part of the frame usually does have a bed body mount and also serves as a place to mount the bumper to and sometimes a shock mount is in this area depending on the vehicle.  Also exhaust hangers extend down from the frame for the tips.  Now since your going in a custom direction like I think you are u can build what ur talking about with the right engineering/design I've seen 1 or 2 on here like this but am not sure where any pics are so someone else might be able to help with that.

Nate is right. The rear frame section really doesn't do much. If you are building something custom, there is no need for anything to hang past the rearend.

thanks so much. if some profiles/pictures would pop up, that would be awesome. again, thanks to both of you.