I think the limitations to becoming a DUST soldier really come down to genetics and their implant.
Genetics is easy. We know pilot implant compatibility is a genetic crapshoot. So is (supposedly) DUST compatibility. Doesn't mean the same individual can't be compatible with both. It may be far less likely, or it may require cutting a deal with someone who can do some serious black medical genetic therapy, but I've never seen anything stating for a fact that the two compatibilities are mutually exclusive. After all, we ICly don't fully understand what makes someone compatible with pilots interfaces.
The DUST implant is a little tougher. It's a brain implant, so that suggests that it's just surgically implanted. However, we don't know for sure (or at least I haven't run across anything stating one way or another) that DUST clones use the same gel matrix brains as capsuleer clones. If our gel matrix brains are specific to capsuleers, then there may be an issue. If all clones use gel matrixes - and I can think of no reason why they wouldn't - then this isn't an issue, either.
Either way, considering how little definitive PF exists on the subject of soft cloning and how reluctant CCP is to make a definitive statement about it (based partially it seems, and this is encouraging, on it's prevalence in our own stories), I'd say you're probably safe to proceed. Especially if, as you've mentioned, it is a one-way door. Capsuleers able to jump clone into DUST soldiers and back does seem to be too much of a stretch.