If you bob yours, it will still be a DA/SA revolver with a hammer you can't cock safely. Ruger's spurless hammer is DA only. Ruger won't sell the hammer directly as a separate part; they want to "fit" the hammer to the gun. They will sell it to you, but only on a replacement basis, and you have to send the gun in for the installation ...
... which is silly, really. I wanted a spurless hammer like you. I posted a "want to buy" on about a dozen forums. Eventually, someone on AR15.com contacted me. He had a spurless hammer that he sold me. I dropped it into my SP101 and it functioned flawlessly as a DA-only revolver. So now I have both hammers and trade them out depending on how I'm feeling.
So look around, haunt the gun boards, and one will likely turn up eventually.