I actually did what you are talking about. I used round-up to kill the weeds first, waited a week, then tilled.

The portion of land I tilled was in a seasonal flood plain area(floods every 10 years or so). The sod was very thick and it took several passes. I actually rented the tiller for 2 days, and tilled for the entire 2 days( about 16 hours ), to make a 1/2 acre. I have used a drag behind disk like the one in cabelas, and it takes many, many, passes to break up sod.

When you are finished tilling, spread the seed and use a roller behind an ATV or lawn tractor to compact the soil-that can also be rented for about $10 a day.

My field came up great, and was 95% weed free! I also limed and fertalized according to a soil test.

Tilling will release seeds in the soil, as well as disking or any other type of soil disturbance, but the amount of weeds is minimal after a round-up spray(even though it dosn't kill the weed seeds). To have 5-10% weeds mixed in your clover is not a big deal, remember, this is not a "cash crop". Continued mowing will help to combat the weeds if the deer don't keep it down for you. If there are not very many adjacent food sources available, and the deer density is high, I'd go with at least a 1/2 acre.

Just a couple hard days of work, proper planning, and your all set.

Jeff...U.P. of Michigan.