A lightweight bike would be nice

I think the 'lightest bike possible' phase is something that everyone goes through. I used to be like that too, until I realised there's much more important things, like looks. Whats the point in having a super fast, super light bike if it isn't shiny as fuck!

I don't care about looks that much. I'm more of a rats and banged up, Mad Max-y vehicles type of a guy.

Sub 7 should be totally do-able, even with strong components. Start saving and build it!
Everybody should have something superlative at one point in their lives.

And yeah -- a sub-7 kilo ride shouldn't be that hard to accomplish. Just need to find sites that have the weights of different components listed.