4 adults? However you do it its going to be cramped if you don't have an awning that can be slept in or a separate tent. It will be a "fun" holiday rather than a luxury one. Its all workable but depends on your preferences and priorities. I think you need to sit down as a group and decide yourselves what is important, what will be a deal breaker, and what you can live with. Bed comfort also depends upon the size and build of the people sleeping in them. A shower over the sink and loo is fine unless one of your party need the loo while someone else is showering....also how do you feel about a wet loo seat? Will you want to cook or will you eat ready made picnic food, get takeaway or take a barbecue with you? Will the campsites you choose allow barbecue use? How well do you know each other? How much privacy will any of you need?