i would just get a dummy release.. Just my .02
Most sporting goods stores sell these bands. You can even get them with a handle so its similar to a bow grip.Go to your local rehab facility and ask them if they will allow you to buy the excerize bands they use on patients. They are color coded for different strengths. I cut them to about 4' long then tied them in a knot so they form a loop. The length of the loop determine the draw weight and it can be changed when your strength increases. I then tied in a d-loop. You can draw and hold using your release, do multiple reps, etc. Extremely good excerize routine.
I think your making a huge mistake drawing your bow with no arrow in it. Wait until its in a pile at your feet - your going to wish you'd never done it.