BD/ Bibler Fitzroy: 2-pole stability?

Hi folks, I got the tent over the summer, and it comes with four poles. While I haven't practiced setting it up a lot, so far its been quite challenging, especially the mid-diagonal poles. The first two poles fit similar to i-tent/ Eldorado and the tent looks decently stable. This makes me wonder if the tent can be used with just the two poles for most but the extreme weather conditions in the lower 48s (mainly the Sierras and Rockies). Any thoughts/ experiences?

How are you setting up the mid-diagonal poles? The easy way is to assemble the poles outside the tent, then feed the pole that points to the left through the door on the right. And do the same for the other pole which points to the right, feed it through the door on the left. They will slide right in. Easy-peasy.