As far as recall, this time of the year they will come down to the ground as little food up in the canopy.
So, pack some hazelnuts....head for the mound behind the church, place some nuts in the branch & trunk nooks and crannies.........wait and they will come. When we went most nuts will get taken for caching but if lucky some Reds will stop and gnaw them open for a snack or three.
Lens wise I had my 100-400mm and I think I was using the full range.
NB if you sit with a nut in your open hand there may be one brave Red who approaches and takes it.
Enjoy, they are such delightful creatures.
PS your post reminds me that we wanted to go again
PPS just saw that you said August, not sure about the nuts as I think they will feeding on natural food high up in the canopy???