Hi,

I understand your pain. Things you could (not must) do:

- have many recommendations on your LinkedIn profile from previous startups CEO you worked for (a portfolio is great, but I also want proof that things went smootly)

- show me that you are a long term contributor to an open source project (I know that many startups are afraid that you are gonna close skype and never "show up" again, I think that could reassure them)

- show me that you have a reputation online (twitter/stackoverflow/HN) if you are an authority I will not be skeptical

- dont be (too) cheap. cheap = low quality

That's my PoV, and again it's things you could do not must do. You shouldnt need to prove anything more than a US remote worker (in a perfect world).