Yeah, if this were for work, I would have the budgetary authority to have a few more droplets. 
The disk space issue is a good one, but monitoring can help keep that under control, at least in my situation. For some reason I thought the load issue would be better if it’s on the same host, but I could be wrong.
What role does Jenkins play in your registry? Does it check pushes to master on some repo, build, and push successful builds to the registry, or something else?