The first key is to do a batch only large enough for your mixer ( hand, or electric) to be able to stir with out stalling or slowing.
I generally am not in the 260’s. My sugar temp normally begins in the 270’s and goes up from there.
A digital barometer is a very hand piece of equipment. Many times when I’m doing multiple batches and my dehumidifier isn’t able to maintain the same humidity my boiling point and finish temp will rise.
A mechanical sift is also a very good investment. Either an electric or hand held that can be used with a cordless drill. The key here is to sift after the granular cools a little.
Oh when stirring I make sure to stir until all steam has left the bowl while mixing.
I geerally do 2-3 gallon batches (mainly 3’s) but I have modified my Hobart that is has 3hp 3phase motor that’s gets converted to 1 phase with a vfd. For these larger batches you need the power to keep the stir going.