32:16 should be ok. Although 32:18 might be better if you are solo just to save your legs a bit. I did it solo singlespeed about 3 or 4 years ago when it was horrendous. The only people out in the midnight rain were the singlespeeders although there was a lot of pushing.
I have removed and re-greased the bottom brackets numerous times. I have cleaned all threads in and around the bottom bracket with a wire brush. Finally whilst out riding I asked who was riding someone where they thought the creak was coming from. They said the rear wheel. I’ve had the cassette off and it looks like the culprit. The pins that hold the cassette together have come loose on the bigger cogs. The creaking only happens in the bigger cogs!