Uganda is a fascinating country to travel around by vehicle. Be fully equipped for spending the night with no facilities at all except perhaps a nearby river. Have a bucket for washing pots and clothes, all cooking gear and all the food you need for the whole journey apart from fresh vegetables. Meat is not always available in the remoter areas so bring substitutes. Most villages will sell onions, tomatoes, potatoes, bread, sugar, salt and oil. You can buy just about anything you need for your journey in Kampala, but tinned food is pricey.
Always have at least twenty litres of drinking water in the vehicle at all times as well as spare jerry cans of petrol. It is best to boil all water before drinking it. Be very careful in towns and villages not to leave your vehicle open and unattended. People with little are easily tempted. You should have no problem sleeping outdoors in designated camping areas or remote places along the way, but get into the habit of locking things away before you go to sleep.