What I have been considering building is a half-Serrurier truss, in the style that has become popular because of Kriege and Berry's work that led to the Obsession telesocpe. This article here, as well as the Wikipedia article on the Serrurier truss, point out that a true Serrurier truss has many advantages over the half-Serrurier truss.
One of the advantages is balance point for the telescope is simplified; you can put the place where the telescope attaches to the mount in a more central location (which is not so important for my equatorial mount). Another advantage is the two halves of a true Serrurier truss work together, allowing much better stiffness for the size of the tubes relative to a half-Serrurier truss. A third advantage is that the length of the tubes is substantially shorter, which both simplifies getting this into a automobile, if that becomes necessary, and simplifies finding off-the-shelf carbon fiber tubes. The downside is that it increases the number of connectors and adds another piece of tube at the pivot point of the telescope -- and this will, I am afraid, increase weight.
Or will it? I don't need as long as a base to reach from the mirror section to the mount saddle -- I can construct a hexagonal center ring out of a piece of aluminum (or maybe even carbon fiber plate) that is 2" wide and mount that to the equatorial mount saddle plate. The carbon fiber tubes can be much smaller to achieve the required stiffness. The big advantage of this approach is that the tubes can still sag, but because the two ends are sagging the same amount, the optical path of the primary and secondary mirrors remains in parallel.
UPDATE: Perhaps I am making this too complicated. I had dismissed a solid carbon fiber composite tube because it would cost me $3200. (That's a bit rich for this.) But I did not even consider the possibility of making a carbon fiber hexagon or octagonal tube form carbon fiber plate. Perhaps I should have. Simpler, less portable, but it would only weigh several pounds, and would drop the total weight of the telescope down to about 45 pounds.