On an R6, if you're running a 180/60 and can't fit a tire warmer between the tire and the swingarm, your wheelbase is too short anyways.
On our race bikes, we use two different length chains to keep the wheelbase where we want it when we make gearing changes. We use 16T front sprockets and, depending on the track, 43-46T rears. If we run the 45 or 46 rear, we use the long (116L) chain. If we run the 43 or 44 rear, we use the short (114L) chain.
Wheelbase effects quite a few things on a motorcycle including spring rate on the shock. Which is why we try and keep it as close to our ideal spot as possible when making gearing changes. The further away your rear axle is from the swingarm pivot, the more of a mechanical advantage the swingarm has on the shock. (Think of it like using a longer breaker bar.)