Dave,
I am curious as to what you plan to use for bows in the design you posted?
I have thrown up a few different houses for growing over the years.
These were cheap, down and dirty, quick and easy.
At one point, I had 12 of them in my yard while growing production tomato's and peppers.
My friends called my place Podville, some were 50 ft. and some 100 ft.
It wasn't pretty, but it turned a considerable profit.
If you plans are anything like this, think about making it bigger than you have suggested.
If you have steel bows, your in luck, it can be any width you have the bows for. I was using 1inch PVC and to get the bow right with a 20 ft. piece of pipe, I had to go 14 ft. wide at the bottom. the PVC just wants to bend so far without stressing. My total height was just around 6 ft, which for me worked out, I had to heat these and it made it easier.
These do not stand-up well in high wind areas, if you have some wind protection they do OK.
Podville was in Montana so weather was a major factor.
I was able to keep them heated and keep them standing through our growing season for 14 years and turn a profit without a change in design.
If you end up using the rolled film instead of poly-panels, look at the available sizes.
Most often, it comes in larger rolls. I'd size what I was building to the sizes of available material.
So, if it's PVC and rolled film, a couple more pieces of PVC pipe ( the cheapest part of the whole thing) and your getting big.
I have never to this day had to much room in any grow house I have built or owned.
Here is another quick and cheap PVC wonder I built in Florida, I wrapped it with shade cloth and did a watering system on a timer. I was leaving the state for 5 months and had no one to care for my plants. I held the rain back with a plastic film on the roof under the shade cloth. When I returned, everything had survived....
It went up in one day and that was a while back. I still use it now to keep some of my plants watered when I decide to run off for days at a time.
Just though I'd drop a few thoughts on ya from my experiences..