Don't we compromise our identification everytime we visit a WG and she see's our face?
I use my real first name, be stupid/pointless not to really. Never given my last name to a WG, and can't think of any reason I would either. I use my own phone (as others, single, not married, no kids etc) but I've checked that my number reveals nothing when Googled, and my Facebook settings are tight. I've never given my email address to a WG - it's either phone call, text, or contact using AW internal messaging system. I have once by mistake almost revealed the company I work for, which again I don't think would be a big issue anyway, but I did think better about it at the time and moved the "conversation" (chit-chat) away from it.
Only once have I contacted a girl who uses iMessage, but my settings don't give out my email address anyway. My only uncertainty is WhatsApp - obviously my number is linked to that app, although I don't use my full name on there anyway, nor is the profile picture a picture of me. And unless someone tries to contact me that way, nothing can be seen anyway (I know this by adding WG numbers to my phone and seeing if they use WhatsApp too, as you can often see a profile pic and/or status message. Only two WG's I've ever visited have used WhatsApp anyway, so I don't think it's a big deal.
I had thought about a punting phone, but then I'm likely to take my iPhone with me anyway (very least to use maps to help me get there, plus I never go anywhere without it, and I don't always go straight home, or go straight from home). Likewise I don't go without my wallet, although I leave that in the car if I'm going to a WG I don't know - I suppose I could do the same with my phone. Be gutted if I got back and found my car nicked though, with no wallet or phone to help me get home! Add to that, the keys are in my pocket when I rock up to the WG's place anyway (although I never park right outside, it wouldn't be hard to find the car if Sergei decides to rob me of my keys, looks at the car logo on the key and goes down the street pressing buttons on the fob!)
Like someone said, it's all about risk management, or risk assessment. If we delve into it too deeply, you'd never leave the house, let alone get to a punt!