XLNT advice and suggestions here.
Steve, I usually unload one at a time onto a bale elevator. The 1010 manual has two sections several pages apart that must be read at the same time if you want to unload one at a time, but I still wouldn't have it figured out if the previous owner hadn't explained it well to me. My Bale Wagon has to be close to level when unloading the 3rd table back onto the tilted and locked second table that the single unloading occurs from or some of the top row may fall off.
My 1010 wagon came from a moderately hilly area and the first two tables had 1" strips welded on as sideboards. I have loaded some uphill, some downhill, but mostly on sideslopes very effectively. The ground I am haying is steep enough to require bench or pushup terraces. Loading on any hillside requires slowing down enough so you don't bounce the bales on the first or second tables. The 1" sideboards on mine may help a lot in the hills, but how rough the ground is limits the speed more than the slope. If your bales are bouncing on the first or second tables and hang over the edge when that table is tripped you will observe a guillotine effect on the overhanging bale(s)!!