I actually dont think that in survival storms that anything other then active techniques work.
PS: on the drogues, The major mistake people make is to slow the boat down too much ie to 2 knots or so. The key thing is to let her run down the waves close to hull speed. Jordan Drogues are often far too effective, especially in your case with a heavy steel boat ( I'm in the process of haveing a new steel boat built as well). Sometimes towing simple warps is enough, In your case the autopilot should manage with warps out ( I often use the autopilot can handle it to judge if the boat is settled).
Active sailing would be my preference, and given my cutter-rig sail set-up (lots of main, relatively stumpy mast, biggish staysail and yankee on a bowsprit), running off is the favoured option.
I would have to experiment with a drogue and I agree...you want to be doing six knots out there, not only to get a lot of helm response, but just to get OUT of the worst of it that much sooner. Warps are an option, as are the old time idea of putting some chain and a tire at the end, but I like the idea of a long, small cone drogue that always has SOME of its length on the waves behind, and has some "give" in respect of shock loading.
My idea is that the JSRs are cheap enough to sew that you could muck about with the design, and either tow shorter drogues, or with more widely spaced cones, until you get the "mix" right...which may mean carrying a couple of the things, one for 40-50 knots and one for "oh, ****..." weather.
The main function of a drogue is not in the speed component, but in the directional aspect, I think. If you think of it as a sort of "super long rudder assist", you can keep your stern at the right angle to the wave trains to both avoid getting pooped and to avoid having gravity itself take you down a wave front like a freight train.
Those are my impressions so far...I haven't been in conditions that merited a drogue or warp of any description, although I have shot off a couple of waves and "submarined"...it's quite something seeing the green water going "up" to the cockpit at speed and giving the crew a good dousing!