No fixed abode
how does it change things

What are the problems?
If you are living the van life, and you have no fixed abode, you can encounter a few difficulties. As a digital nomad, you may have set up your van as a computer workstation, but you may still find it convenient to use the public WiFi in s supermsrket cafe. Obviously, you will need to observe the parking time limits, if any, for the supermarket. There is an increasing number of car parks that are introducing restrictions, and although these would appear to be contrary to the interests of the supermarket, very often the car park is not owned by the supermarket, and the owner sees parking charges as a source of revenue. The charges are often imposed when you have not committed an offence.
If you feel that a parking charge invoice should not have been issued, then you should appeal as quickly as possible. However you may encounter two problems with this process. These result from the unwillingness of the parking management company to respond to emails or telephone calls. Using traditional mail services requires you to have a printer, and using one in a public library could leave you vulnerable to further parking charges and other costs. It is also extremely slow, as you probably don't visit your accomodation address every day.
Your first difficulty may come from the fact that you will be using an accomodation address for your vehicle registration. Ypu will not have received a window sticker at the time of the alleged offence, but the management company will have written to your accomodation address. In my case there was a two month delay in my collection of the notice, and follow up letters. Parking Eye do have a late appeal process, but it requires you to complete an online form. This has two disadvantages - you don't get a hard copy of your submission for your records, and you probably don't want your friend at the accomodation address to be subject to the follow up persecution of the management company. In addition, you may not want your friend's assets to be subject to any court orders, or to have an effect on his credit rating. This problem could be circumvented fairly easily if you were able to use email, but the parking management companies don't like this. I can only assume that this is because you are able to keep a record of all transaction and interactions via email.