+1I understand your thoughts though. I hate wasting anything and can not stand seeing bad meat handling by others. Here is an outside the box thought...maybe get a salvage permit for a road killed deer (fresh obviously) and practice on that. Not sure of what kind of area you are in but I could easily get a fresh deer a week just from the trips I take to run into town to the hardware store.
I learned to field dress, gutless, quartering, and processing my own meat by using carcass tags given out after a vehicle/deer collision. Usually the local county sheriffs office handles these tags. You would need to call and ask because there could be an established list they use to call people when a deer is available. The tags should be free. They will call when one comes available.
You’ll easily learn the gutless method doing this. You can even practice caping. Vehicles can leave some meat in a mangled mess so you can also get comfortable cutting into the deer from certain areas of the body without opening the whole thing.
If you choose to learn this way, always ask the condition of the deer before going out to the scene so you’re not wasting time on a deer v semi etc.
I used this experience to quarter out my first doe Antelope and first doe whitetail in the field this year.