[bitfolk] OpenBSD guest?

Hi all. Have had bitfolk recommended and it has been said that custom ISOs can be uploaded, which I've also read on the website. OpenBSD 5.9 and 6.0, last and current releases, have native Xen PVHVM drivers. Is this enough for me to be able to install OpenBSD into a guest instance? Am I also right in my understanding that the guest OS must have an ext2 or 3 boot partition? OpenBSD uses ffs, so I'll have to find a work around there, I assume? TL;DR I'm looking for a VPS service, based in the UK, that I can run OpenBSD on. Can this be done with bitfolk?