Sharah's 2017 Nissan Camper Van with Roof Nest (did not use roof nest) is very, very basic. The idea that it sleeps 4, while I was the only occupant, is a reasonable expectation, however the 1/2 bath idea is a huge stretch. Sharah was very nice and at my prompting, included a simple solar black bag with a hose attached that could be filled with water and left in the sun for a few hours would probably work. She also added a fold up portable camp toilet.
The Maui beaches have showers that are very pleasant, natural temperature, and while I was a little self aware of soaping up my body, in a bathing suit, and showering in public view at a facility intended for surfers / swimmers to rinse off the salt water, the public showers worked fine. I later saw one or two others soaping down also, LOL. I ended up being able to use a friends bath room with hot water to shave every other day so that was my only issue. I went into this, as a 75 year old asking for adventure and I got what I asked for. But each day of my visit I was actually in a workshop seminar thing and needed to be somewhat presentable. I was blessed with making friends that help make the experience a little easier. My main issue was that I needed to be on the north Hana Hwy. area about 5 miles after the Hana Hwy. changes from 36 to 360 everyday and all the beaches in that area do NOT allow camping. I later found that the ONLY public beaches on Maui where peeps camp is just south of Lahaina, there was a stretch of Hwy. 30 that looked nice but it would be very noisy with all that traffic going by all night long as that is the busiest stretch of road on the island. That area is a long ways from where I needed to be every day. Camping on Maui is NOT easy, at least my older guy experience. I stayed a couple of nights where obviously those without homes have chosen to sleep.
Otherwise, Sharah was a wonderful host in every way, no complaints there whatsoever. If you are up to the challenges of camping on Maui (and don't care about hot water to shave and bathe) this little camper van is a great way to save some bucks on transportation and living at the same time as you do want to travel around and see as much of this beautiful island as possible. Affordable accomodations in Hawaii are non-existent! Go for it!