So, high aspect ratio is desired, but needs support... why not extend the trusses for a biplane design?
Not an aeronautical engineer, but from my armchair seems like high-aspect ratio and support are both gained by using a more familiar technology (I've seen pictures of real biplanes flying, have not yet seen a truss-braced like this concept in the air).
As with all engineering, there is a tradeoff involved, and with biplanes you don't get double the lift because of the boundary layers of the wings interacting.
You also pay a drag penalty as you have twice as much skin area exposed to airflow, and it complicates the design because in the transonic région you can get interactions between shockwaves causing flutter and other not so fun effects.
We now have sufficient materials knowledge that we don't have a problem making wings long enough to lift the plane. We're instead working on reducing the drag, so we can make engines work less hard.
Mentour Now! video on Boeing and transonic truss braced wings: https://www.youtube.com/watch?v=zkrdIw8LWrM