I got the 5-fraction SBRT, total 40 Grey, without the SpaceOAR.
(I believe that the spacer should be injected the same hour as the gold seeds fiducial markers are implanted, so I asked my care team if I would have it. I was told that they give it to patients who couldn't have the gold seeds implanted; as I had the markers I didn't need the spacer.)
I noticed some mucus and little blood on my bowel for a few days post-SBRT. I reported this to my radiation oncologist. Somebody in this forum indicated to me that the mucus was a sign that my rectum was healing, and with the blood veins still sensitive the bowel picks some blood . I trust/hope that our support group member is right. The bleeding stopped after a few days, not even a week.
I am now nine weeks post-radiation treatments and feeling great. I would still have liked the SpaceOAR, perhaps it would have prevented the bleeding.
I don't necessarily question my care team's saying that I didn't need it. My treatment in Canada is taxpayer-funded, so I get what is really medically necessary, not what I wanted.
(I think your U.S. private insurance will let you get SpaceOAR.)