definitely a nice set up...
the wife and i did a recent trip where we were out in the desert for around 10 days and used a small shower tent and just heated water on the stove and did fine with a washcloth and bucket. i did come home and purchased a bug sprayer shower off amazon that we will use next time. the tent was under $30 and the bug sprayer was around $30, so it is a very cheap and versatile set up.
i like your set up because the tent is better suited for wind. we have the little portable shower tent and the west texas wind at night was a bit much for the little tent. one gust of wind threw the tent in a pile of cactus and that didn't turn out very well. so, having the more rigid mount and better curtains is a definite plus...but, i'm not sure how having it right against the vehicle would work. we like having the portable tent and setting it up where we want. the road shower is nice. definitely convenient to just plug in a hose and be able to knock the stink off of ya without having to heat water in a pot like we do. not sure if i would want the extra weight and gear, but definitely see where it is quite handy.
the set up is a little spendy, but if i did nothing but remote camping and did a fair bit of it...i would think that it was a good value. we also do a lot of campground camping and usually have access to heated showers, so it would not be as practical for our current travels.
i can't sleep if i'm stinky and sweaty, so if all i did was boondocking....i would probably go with a setup like that. when my sleep comes into question...i can easily justify spending money