Proxy server with 3/4g dongles

I would like to have a Raspberry setted up as a proxy (squid should be a good choice), to the raspberry i will attach "X" USB 4G dongles and i want a proxy made out of each usb attached, with his own username and password and i want to be able to access them from my vps. https preferred I would love to have the option to disconnect the dongles or reset the rasp to get a new ip from the mobile carrier at request or every X minutes. This last part is not strictly required but preferred. I will need to know the basic commad to make it work and to add dongles as needed. Thanks