This is pretty easy to do with a little time. IDad and I run a land fill and do this alot. It takes nature 15 years to make and inch of topsoil, but can be speeded up consideraly. When they built the Tenn Tom water way here they stripped all the topsoil and clay off the path and it is pure sand underneath. Several million yards from each cut in nothing but sand. The topsoil was used to cover spoil piles. Some of this was to be recreation and animal habitat and had to be grassed. They sowed and fertilized buck wheat and when it got on up before it dryed they turned it under with 2 and 3 bottom turning plows disced it then replanted. then again whil it was still green they turned it unedr and replanted I think they did that one more time then planted it in serecia and clover and lespediza. That was in 79 and just the other day I helped dig a core sample and it was 1 foot deep on what was pure white sand.
The hay idea youd work great to, holding down the eroision and helping put nutrients back into the soil.
Back in the 50s and 60s when the interstate highway system was being built in Texas, my father sold bermuda grass sod for the ROW. They basically cut/scraped the first 6" of soil and hauled it out in dump trucks to spread on the highway. It wasn't the organized operation like it is today. We were left with thin sandy soil.
My dad bought some button clover hay to feed to our cows and spread it around the property. Some of the clover sprouted and took hold, but since nothing more than that was done, it really didn't ever recover. When I sold the property in 1998, it was just beginning to recover, but nothing like it had been before the sod removal. I just can't imagine hay doing that much to regenerate the topsoil. I think Taylortractornut has a much better plan. An agricultural Extension office in your area might also have some good advice.
I had 15 loads of "fill" (aka clay) dumped 3 years ago and then spread it with a bulldozer. Since that time, I have spread wood chips on it, turned it into the ground with a 3 bottom plow after spreading a lot of pelleted urea on it (wood chips suck the nitrogen out of the soil). After 3 years, the chips are 75% broken down and the clay has started to magically turn into great looking soil. This years crop of soybeans actually grew (wood chips suck the nitrogen out of the soil )!
If I could get leaves, I would use them. But, no ready supply.
You think A rototiller would get plugged by a layer of old hay a couple of inches deep? I'd like to do a couple acres, too much for a tiller? Got a new Mahindra 2615 and not sure if a 5' tiller is too much.