Uhh...? That's very short sighted.
It's one thing to not want to build a quick linkbuilding bot with a programmer who might take it and use it (if they do SEO), completely different for an entire business model.
The thought of a remote worker approaching one of my clients and actually landing them is laughable. I would say you're selling yourself short.
For all those areas you will want TeamworkPM. Trello would be a huge pain for client work like that and doesn't cover all the areas you mentioned. You would have to pick up additional programs like Toggl (time management) if you went with either Basecamp or Trello.
http://www.wickedfire.com/shooting-the-shit/179570-any-basecamp-users-here-share.html
Idea for automation with any of these programs:
http://www.wickedfire.com/2247084-post13.html