You may find that your rectangular bag might fit over your hammock. Just unzip the foot a little and put your suspension line through the opening. You can push the bag toward the foot, get in, and pull it back over you. I have used this method many times for friends trying out hammocks. Of course, if you need a bug net that does not completely encircle the hammock, this won't work so well. Good luck with your set-up.
...and there came to be a day, all too soon, that I became aware that I could travel no more on my long journey. Though I did not arrive where I had planned, I believe that here is exactly where I am supposed to be...