Ba r r y writes:

Steel studs are common in commercial construction. I haven't seen a
wood stud in a phone building for at least 15-20 years, regardless if
the wall carries a load. Lots of these walls have counters, cabinets,
etc... mounted to them. A lot of this stuff is installed as an
afterthought, so the wall was not specially designed to carry the
load.

I did some web searching on this a while back, and found a number
of people who claimed to be hanging cabinets from steelstuds with
no problems (I don't know what guage of steel they were using).

I assume the success rate would vary with the amount of weight
and the number of screws (and whether you're using screws
designed for steel studs). It seems to me there should be some
kind of rule of thumb for weight-per-screw. The screws seem to
grip pretty well.

Another possible strategy is to arrange things so that something
else takes the weight, and the studs just hold it upright.

The OP said his walls weren't up yet, so I'd certainly add wood
blocking wherever it might come in handy. For an RV, you also
have to consider dynamic loads. I like the idea of a french
cleat, with a peg that has to be removed before you can lift the
cabinet off the cleat.