No heavy training - just a lot of dealing with people, reading, etc... Grew up on a farm too...
One thing to remember is that a LOT of folks can quickly become unraveled... IMHO, the primary objective is to prevent panic and shock. If you can control the mental component of shock, you can handle the physical components. Lots of folks die because they think they are gonna die. Lots of other folks live, after worse stuff, because they don't think they're gonna die.
In addition, pressure bandages, clotting, etc., tend to "start to work" better if blood isn't actively flowing. A temporary tourniquet won't cause any harm, other than bruising. Ever had your leg go to sleep? Or have your ol' lady decide to nap on your arm? Same basic thing...
If you have someone get stuck with something, and it's still in them, that something has now become known by a different name: The Plug. Do NOT pull the plug. Cut it off if it is attached to something, and it can go for an ambulance ride too. This is what God made bolt cutters, hacksaws, compressors and cutoff wheels for.
If you have blood spurting, and a conscious patient, you have a reason for them to maybe panic. No blood spurting means less panic. Stop the bleeding, then assess the situation, and if you can clean/clamp or deal with a pressure bandage, then go for it. By now, you should have the chopper on the way... 15 minutes with a tourniquet isn't going to cause any problems. 15 minutes of spurting and flailing... Well, maybe 5-10 minutes...
If you've got longer to to, and get nervous about the tourniquet, you can loosen it every so often. Just try to not let the patient drain out with it loosened.