I read your post and can only note that such narrow specifications are your choice, but ... It's a little too far off the mainstream of usage models.
Have you considered writing such an application yourself? You have wget and seem to just want a GUI on top of that. If so, you could whip something up in Visual Basic in a week or less.
Sometimes you get to create your perfect app.
Do you know what wget is? It is a command-line website downloader/mirroring tool. It also has a GUI version. It does not need any install either. You just unzip to a directory and start using it.
My question then is.
Does anyone know of any software with the same 'no install needed feature' and a GUI also that I can use as a substitute to download websites for offline browsing.
PS: I find wget a bit too demanding with the command line.