If I remember correctly there are just four bolts that screw up into the rack..once they are off it shoudl be loose.. but maybe a PO sealed/glued the pipes to the lid??? Try driving a putty knife between the lid and the rack carefully??
I went the opposite route and turned a gl1100 standard into an interstate... It's a real bear, and it looks like there's no easy way to get it off. You're correct. If you can pop the side with the hole, the other side is just a slot.
that looks like an interstate and should be similar to aspencade, does your top box have to locks below the luggage rack ? if so these need to be unlocked and then the box should lift from the back and slide backwards
I know cos I'm just stripping mine to repaint and have just took everything off