I always mount my epiphytes on the "rough" side,
@Seaecho. . I don't use "tubes" though. I purchase large, almost flat slabs and cut those slabs to order. You could use either side though.
The bifurcatum certainly will grow large, after 5 years or so, but the 'Neatherlands' tends to grow a bit slower and not get quite so large. That being said, you can always divide the pups off a bifurcatum to control the size. I have "harvested" many dozens of pups over the last 25 years. A five year old plants might have a half dozen pups and thus, you could end up with seven stand-alone plants, and do what you wish with them. I mount and repot staghorns all year long. They don't seem to care what season it is. Heck, I just mounted two today, a custom-order for cork mounting.
Having grown several hundred staghorn ferns, I have quite a bit of experience in growing them. It still puzzles me when I look at that first picture you posted. My thoughts that these were some sort of traumatic lesions got shot down, so I just don't know.
