A couple of notes about the RB.. First, the 178mm f2.5 Aero Ektar will NOT fit the 4x5. The rear of the lens intrudes and hits the mirror.
I bought a Super D planning to use an Aero Ektar (back when you could get one for $50). However, it will fit on a 3x4 RB. I dont know what other mods are required.

2nd, there is an issue of longer lenses, where the mirror bumper on the bottom of the box will cause a vingiette ( on the top of the image). This is more pronounced in portrait format.

3rd, the Super D actually has fairly small lens boards. A large lens like the Aero Ektar may not fit at all without a modification. The older RB i think takes more standard 4x4 lensboards, but you should ask before buying.

All that said, the RB in any form is a lot of fun. It is bulky, but not really heavy. I had a heavy duty monopod (center column from a Tiltall) that really made it nice to use.

There are some roll backs made for the graflex cameras in their various sizes. Many fast lenses will fit as well, and petzval style fast glass makes a good home.

The slotted holders are expensive since people know they are hard to find.