A blog... maybe, do you have a good vision of what kind of content you would be putting into the blog? If not, probably not. A blog without regular content is pretty pointless and will look strange.
A forum... no. Can't imagine how that would work for a portfolio. You don't want an open discussion of the portfolio going on. And you'd be forced to constantly maintain and police the forum for content that isn't appropriate.
@julian I am not running any other active forums or DO droplets to move the demo site to. I have a DO account just for the demo site. I will delete the droplet once I install it for free some where else.