I was definitely joking about the copper slab

come on man... haha. And I'd wrap them in electrical safe to be safe, that's just me though. I like the idea of heat shrink as well.
And the only solution I have for your space concern, if you don't want to move your amp, is to have toolmaker make you custom inputs that have a 90 degree angle, so you're not limited on space any more. They wouldn't be cheap, his inputs usually cost like... $40 or $50 I think, but they are TOP-NOTCH, and gorgeous. HJere's a link to his stuff:
Show off your "Toolmaker" goodies here - Car Audio Classifieds post #5 shows off his inputs. They are all made however you like, so you'd just have to tell him your requirements. And he's the link to everything else you'd need to know:
(Tool Maker) - Car Audio Classifieds