I think you have a good plan here Hoco. I have messed around a bit with changing strut lengths from the ideal and never had any problems.

I built a couple of tensegrity octahedrons where one side of the octahedron was about 16 feet and another side just 4, in order to get the shape I wanted for a sort of cantilever support piece. These did quite well out on the playa 3 years running.

I modified the strut lengths for a 2 frequency octahedrally based dome less radically than that, to fit the struts I had available, and again, it was totally solid.

The only thing I would keep in mind based on my experience is that longer struts are "weak" in the middle, if someone is stepping on them, or will be liklier to deform if put under a lot of compression load, which can happen when you deviate from an ideal structure-- the load won't be transmitted as evenly to all vertices.

I built my modified 1v this weekend and I ended up making the top pentagon the same size as the floor pentagon. I used 10' struts (e.g. uncut EMT sticks) for the top and bottom pentagon. I cut 8' 3" struts for the sides (then pressed them and drilled 1" from the ends). This made the vertexes around the top easy to reach but still overhead. I made the top five roof struts (that meet in a peak at the center) 9' long.

The result is a dome about a bit bigger than a 2v optimal dome, with more vertical sides. I can put it up in a few minutes, without a ladder (I attach the five roof struts together first and then attach them to the top pentagon second, so I never have to reach the top vertex). It has natural door openings -- no need to duck when entering. Plenty strong. :-)

The struts cost me about $150 as EMT has gone up to almost $6/stick.

Wow. I was contemplating a build like this, for the same reasons - roof peak too high, floor space too little with 8' struts on a starplate dome. After doing some recalculations, I came up with my own strut lengths, but remembered you had posted something about this a while back. Not sure if it was intentional on your part, but did you know your wall struts (top, side, bottom) form "golden triangles"? To second Bruce's musings about deviations from ideal geometry, I want to share a brief journey that brought me ultimately to the same strut length/angle ratios as you.

In researching pyramids for a structure build for BM 2009, I was bothered by the fact that what seemed to be a "perfect" square pyramid should actually be the upper half of an octahedron. That way, all strut lengths are equal, and the triangular faces are equilateral... all in perfect symmetry and balance. But nobody talks about these kinds of pyramids. Everyone always raves about the perfection of the Great Pyramid at Giza, and all those others built with approximately the same angles and edge lengths. They didn't seem as universally perfect as the octahedral type to me, since they lacked its symmetry. To make a long story short, I ended up discovering there are all kinds of deliberate reasons for the pyramids being built according to their geometry. One of which was the architects' use of the golden triangle. You probably already know this, but I'll post it for anyone interested like I was: A "golden rectangle" has side lengths of 3 units by 4 units. A diagonal drawn from corner to corner yields a line of 5 units. Now, if you split the rectangle along that diagonal, you get two right triangles, with their hypoteneuse of 5 units. If you join the triangles along their 4 unit edge, you get a "golden triangle." That would be an icoseles with lengths of 6 by 5 by 5 units. This style of triangle was apparently big in Egyptian architecture, and evidently a circle drawn along a vertical axis from the apex of a pyramid (Giza type), around the underside, and back up to apex will have a circumference measurement equal to the perimeter of the base square, when that circle's radius is the height of the pyramid (i.e.: squaring the circle, which holds implications of a drawing together of the earthly and the divine). And of course when you start talking "golden" anything, you get into sacred geometry, and all those ancient mystery religions surrounding mathematics.

So, I just wanted to comment on ideal geometry. I found it fascinating that what I thought to be deviations in the case of the pyramid structure were, in fact, quite deliberate. And look how stable those structures have been over the last few thousand years! In changing the symmetry of an icosahedron, I'm really glad to see you didn't experience any structural weakness, and I love musing about the language that geometry speaks in. I may very well follow suite here, and build a couple modified 1v's for the 2010 burn. Mine will likely be made of wooden 2x2's of 8' and 6' 8", proportionally the same as your 10' and 8'3" struts. Thank you for posting this idea!