I gather that you've never visited the US as your characterization of US parking spaces being universally a lot wider than in the UK is not well founded. The size of parking spaces here varies widely depending upon where you park and where you go. While many shopping malls and big box stores have large parking lots with plenty of room for sizeable parking spaces other locations with less real estate to spare will crowd parked cars together like sardines. There are some nearby stores and restaurant where I simply can't park my truck in their tiny lots. It's always amusing to hear the assumptions and stereotypes about the USA voiced on these pages. Just yesterday I had to wedge myself into a parking spot where I could barely open my door enough to exit my truck and had to literally touch the other vehicle's door handle with my door edge being careful not to damage anything. There was little room on the opposite side as well. Anyway, the photo you posted of the three vehicles parked side by side would not be atypical here in America. BTW, the truck in your photo is a Nissan Titan, a full size pick-up truck. I drive a Toyota Tacoma mid-sized pick-up that is smaller, with a cab and bed that is somewhat lower to the ground.
While it is hard to tell because of the barrel distortion in this photo, note that my camera's perspective at 5 feet off the ground (pointing downwards) is at about at the midpoint between the top of this vehicle's window and the pavement. At any rate, even at this close range the Mobius C2 lens is doing what I want it to do as a side cam.
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Not much later I was in a different parking lot where there is plenty of room between cars but the parking spots are so short that my pick-up truck sticks dangerously out into the flow of traffic.
(Notice the red SUV in the distance that has much taller windows than my Toyota mid size pick-up.)
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So, your post got me thinking about the height of my rear window camera mount, so I measured it and the camera is 5 feet, one inch from the pavement. Then I spent the day observing other vehicles around town and discovered that this was slightly higher than many other vehicles but lower than various other pick-up trucks as well as even some passenger cars. Several SUVs even higher (taller) windows than my truck. On the lower end, compact cars tended to have the highest point on their rear window at about 4 feet from the pavement. Cross-overs tended to be higher than compact cars for the most part. Anyway, this was about the average range one could expect, except for some outliers like sports cars. Oh, vans like in your screen grab tended to have taller cabs and windows than many pick-up trucks.
This thread got me thinking about my six or so years of side camera experiments and this motivated me to take an inventory. I realized that I've experimented with nine different side facing cameras and 12 different lenses. The Mobius cam with a C2 lens has proven to provide the most ideal coverage for my purposes. Obviously, with each camera and each vehicle the results will be different. With each camera and lens I've tried, it took some trial and error (what you are calling compromise) to find the optimal positioning for the particular camera and lens. In the end, some cameras proved ill-suited for side camera use while others were much better. Some cameras just seems to perform better as well but that's more a function of DSP and sensor. Camera height surely plays a role but ultimately, everything else aside I think choice of lens is the primary factor in choosing a good side camera.
As for how low to aim the lens I suppose it matters what kind of coverage any given camera can provide but experience taught me that it was vital to have at least some amount of very close-to-my-vehicle coverage for parking as well as the possibility of a side impact while driving. For parking it's good to see down to the pavement as much as possible, especially for door coverage and the possibility of vandalize. At the same time it's obviously important to have a full view of the adjacent lane of traffic as you point out in the image of the van cab that gets cropped out. For this reason, after thinking this through and reviewing your footage and stills I am no longer quite so impressed with the B1W as a side cam as the lens coverage just seems too narrow (both height and width). Other similar screen-less, tube style cameras may be better choices and there are many on the market these days. I had good luck with the mini-0806 and mini-0906 for this use as their FOV was better for suited for this purpose.
BTW, speaking of huge USA parking spaces here's a three year old screen grab shot at a nearby Walmart store. The parking lot is enormous (I'm parked somewhere near the middle.) and the spaces are the longest and widest I've ever seen anywhere! It avoids many of the tight parking problems, dented doors and other typical conflicts people often experience and makes it very easy to park there which I assume is the reason they provide this much room. Cars can essentially fully open their doors with ease with room to spare.
This image is from a
G1W-H fitted with the original Mobius C lens.
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