In the log I noticed:
Testing bitcoind RPC connection to 'http://127.0.0.1:8332/' with username ''
So I went back and set rpcuser='' in bitcoin.conf
And I ran p2pool again this way:
run_p2pool.exe -a myrichwalletiwish youwish
And still it didn't work. So I went back to a normal pool, because I have other things to do today.........
It's not really helpful but it just works for me. It grabs the rpc credentials from bitcoin.conf. Are you running it as the same user? (Wait, I see you're using Windows so you probably are)