Yes, that is reasonable. The test garden I did was in a fallow field growing on clay fill dirt. It was pretty bad. Tilling was necessary to break up the crust, mix in the covering tall grasses and to fully mix in the compost. This was with a tractor tiller to a depth of 10-12". That got us off to a surprisingly good start the first year. Much better than expected. You can plant afterward or cover and may not need to till again. Weed seeds are a fact of life. Mulch heavily to keep them minimal. Grass clipping work fine if you have a grass catcher and the lawn has no pesticides or weed killer applied to it.The intention this year is not to plant, just get a start on the space and try to mitigate as many issues and weeds as possible this year. If that seems reasonable? I do have access to small implements for the tractor (3 furrow plow, small disks, and small cultivator) which may be helpful if required. My wonder is, if deep tilling (plow) is going to expose more weed seeds that may be deep in the soil? As stated earlier I was thinking I would add some new topsoil (4-6") and approximately the same (4-6") of organic compost. I could also get manure as there are most types of the typical animal farms nearby.(cow,sheep,goat,chicken,horse)
If you add manures I would be sure that they were not fed any hay from fields that had an herbicide applied to control weeds like thistle, etc. If none, then yes, add some manure too. If herbicides were used, then skip it. Test the soil before adding so that you amend accordingly. A full panel test will provide the carbon content, pH, N-P-K values, and key element content. I get mine done by the county or by mail at the UMASS in Amherst, MA.