On a really large RV, I might want to stick to the left/right configuration mentioned above re hookup location. On a DIY truck camper, I would put the hookups wherever they are most sensible given your camper systems design. E.g. for water, I would personally prioritize resistance to freezing, ease of filling, access to pipes for repairs, etc. Extending electricity and/or water hookup isn't that difficult on a vehicle that size and, if your experience is anything like mine, you will have a bit of flexibility in your parking orientation given the smaller vehicle size that allows you to make the most of the site (privacy, light, views, etc) in ways the big RV's can't.