Today I spent some time riveting the bottom right skin. I was able to rivet all then way up to the j-channel. So far it has been straight forward and no issues, but I suspect it will become increasingly challenging as I get closer to the main spar.
I slipped in the j-channel, making sure to go between the inboard j-channel and the skin, and then clecoed it into position. I then checked the clearance between the j-channel and the rib cut outs, and everything looked good.