I shot a classifier at 66% yesterday. I wish I was shooting anonymously...
I wouldn't recommend creating an alias. At least, I wouldn't go to a match and introduce myself under a fake name. The competition community a relatively closely knit one, and a lot of things are based on trust. There are obviously assholes and cheaters everywhere but most people I've met were good honest folks. I wouldn't join that club under any name other than mine.
Firearms competition is an explicitly public activity with use of guns. I've had my patients and colleagues bump into me as I was moving my shit between the stages (one of the local clubs utilizes a public range). If strict anonymity is required, the only answer is not to come.