The RUM factory chambers all have long throats, at least all of the ones I have loaded for and heard of. The one I am working on now (Sendero) has a mag length of 3.700" and the 200 gr Accubond hits the lands with an OAL of 3.785". So in order to stay away from any problems with the tip of bullets hitting the mag during recoil or being broken off while being loaded into the magazine, I seat them at 3.625". IMO you can accomplish the same thing as seating depth variation with slight changes in the powder charge, it is all a matter of barrel timing
IOW don't think that you can not find an accurate load just because you can't seat close to the lands.
The Wyatt's box is interesting though and being a DIY guy, I am interested to see if anyone has done the installation themselves.