That sounds like the best idea, use the garden tractor for tillage and the utv for spraying. However, for the price of the small disc, it might just be easier to hire someone to till the soil for you, and get your clover or whatever seeded and established, then just use your equipment to mow and spray the plots. If you mow clover twice a year, keeping the mower set as high as possible with your equipment, and spray for grass twice a year, and frost seed the thin spots every couple years, your clover plot can last up to twenty years or more, with no further tillage. There's a big difference between a 27 hp garden tractor and a 27 hp compact tractor, a 27 hp garden tractor pulling a small disc to try and till an acre to prepare a seedbed is going to be like scratching an elephants behind with a toothpick. Good luck with your plots. There's nothing quite as satisfying as hunting over a nice green food plot that you've planted yourself and watching the deer come out and start eating!