Building a hay spear for my skid steer. Do you like the double fork spear design or the single spear with two shorter prong design? Also if you go with a single spear, any concerns with mounting the spear towards the bottom of the back plate to get more clearance when you're loading a bale in the back of the truck.

Majority, I see with a single spear the spear is always at the top of the attachment. This makes me have to stab the bale a little higher than center in order to pull the spike out after I load it in the back of the truck to clear the bed rail. I've had a few bales come apart on me when I'm stabbing him a little higher.

Made a single spear, no small spikes for my backhoe. Didn't want to be taking the bucket off all the time, and I have quick hooks for forks welded to the top, so took a piece of 5/8 thick X 12 inch wide, and a bit longer than the bucket is tall. Got a piece of round stock about 36" long, welded it to the top of the flat stock, to hook in the hooks on the bucket, welded a piece of angle Iron on the bottom of the flat stock so it would slide under the bucket, torched a hole through it and ythe bucket for a 5/8 bolt to keep it from flipping up when pulling out. Then hole for the bale spear, a bit higher than center. Have never missed the small spikes.

I like the smaller spikes for stability when stacking bales. I had a single spear on the backhoe bucket at one time and if I grabbed a little too low so I could more easily get the bale high - at the least opportune time the damn bale would spin on the spike. That would frustrate me - so 2-3 points of contact for me.

Dimensions would be great. I'm all in on the double spikes and thought also about using them as forks too for feed bags on a pallet….

Depends a lot on how you are going use your bales. If you are strictly going to be picking them up, stacking them, then loading them again for selling….the two horizontal long spears mounted lower is good…..unless you are stacking in a barn where you need to put the bales next to a wall and need to offset the bales….In that instance the single spear with the two short stabilizer spears down low works better imho.
Also if you dropping them into hay rings or for hay huts on their ends, the double horizontal spears make it harder to do to me.

Edited above to add photos. The double spears are 31.5 inch center to center and the frame is 3x3. The top u shaped piping is just a safety stop that gets used as a tie off occasionally.
Priefert Manufacturing made that one originally but it's been patched a few times.

While here, I'll add the newer double bale loader which has a 6 ft width. With one on the front end loader and another on the 3pt hitch, we can move and carry 4 round bales. It works great loading 20 onto a double cradle hay trailer, doing 10 loads instead of 20. Everybody in our area with a big enough tractor in the hay business has these large double bale loaders.

Go with the 2 long spikes mounted flat on the ground. We've been using these for decades and they are much better than the single spear type.

There is a type out there that has two long spikes and a 6000 lb capacity, but it won't sit flush on the ground due to how it is made. Would trade it in a heartbeat for an Armstrong Ag type design.

Saw a bunch of 2 prongs at an auction last week for $350 a piece. Keep an eye out and you might not want to have to build your own.

Beware of the type of spear point, as ones that are too big of diameter can cause issues stabbing and getting bales off when loading trailers. That one is probably 20 years old though now, and the newer designed spears are better.

Like the 2 flat lowers as they seem stable for high placement. Guess when I am lazy and do not want to go back to the barn to put the bucket I will use it to move brush.