That's probably not enough to justify purchasing expensive equipment. You're probably just going to have to practice getting your distances right. Maybe make some passes, then measure the distance between the tracks.
I've found it better to make passes at the ends for turn around areas, then make back and forth passes next to each other turning the sprayer off at the ends, rather than making smaller concentric circles like you might do while mowing. Don't know if that would work in your lawn though. Making turns with the sprayer on always leaves gaps.