Yes, it can be done. I'm doing one slightly larger than yours on my little machine right now. I also set up the ironing board at table height to help support the quilt. Like Elizabeth...I just stuff the quilt through the hole until I get where I want to go. Rolling seems to make it too stiff and large for me to handle very well. The 505 will work out really well for you..start quilting in the center so that you can reposition if you need to with the spray. Just make sure you have plenty of extra batting and batting around your top so that if it slips a little...you won't be in a mess.
Good luck!