I found the side effects were quite gradual and luckily not too bad all things considered, be glad when I'm off the stuff though!!
SBRT does sound like a good plan if it's an option, though again I was lucky as not too far from the hospital and the majority of my appointments were in the evening so after work.
Supposedly it only takes two to four weeks for your testosterone to hit rock bottom so should stop cancer progress in its tracks so I wouldn't worry (easier said than done I know). Did you get the injection in your butt!? Mine have been in the tummy.
Cheers mate