I think the more useful approach would be to model some of the more popular tube rack power amps (Marshall, Mesa, VHT/Fryette, Soldano, Rivera, Engl). This way, you could build a "virtual rack" in Helix or as I would love, run an actual tube preamp into the modeled tube power amp for recording and thus eliminate the need for a load box. Yes, not the same as a full head but close enough.