The Atalanta has always been used as a caravan en route to a new cruising ground.
The issues you need to be aware of are:
Where to spend the night?
Camp sites seem the obvious choice. Not always that easy though. We have done many trips across Europe, usually staying overnight in campsites, largely because of having children with us.
We usually book campsites in advance and send photos of the car and boat so that they know what they are agreeing to! We have had camp sites try to refuse us entry even when we have booked. In th eUK there is always the problem of where to spend a night and we have used Caravan Club sites. Just ignore the “it shouldn’t be allowed” comments from caravaners!
In recent years I have been making these journeys with a son (they are now adults), or another association member. So our needs overnight have changed. We often spend nights in the service stations among the lorries, or caravans where specific facilities exist. We have never had any problems. However be aware that the advice is not to spend nights in service areas because of the risk of being mugged. So think about security. Choose service areas with fuel – they will be busy all night. Park near the buildings, not at the far end of the lorry park. Avoid the “aires” which are only picnic areas – you might be vulnerable there.
Some form of ladder is required so that you can get on and off the boat safely. We use a stern ladder permanently mounted. It is useful for swimming when we get there anyway.
There are of course toilets in the campsites and service areas. If you want to use your own toilet it will have to be of the chemical toilet type, or fitted with a holding tank.
Water will of course be available in the service areas and campsites. Just worth mentioning that to keep the weight in the boat down we use a small container of water with a tap on it, and leave the boats water tanks empty until we are afloat. 40 gallons of water would be very heavy!