This ship part always really bothered me because how does thulium (and not durantium) make your hull stronger and the effect is not even strong enough to warrant use of a strategic ressource. I always saw thulium as being used for sensor systems.
Maybe change the prototype part for thulium to thulium targetting array with +25% accuracy for just that ship. Still a niche choice, but at least it makes sense. Or there already exists a protype sensor module, which I think uses thulium, so thulium could be left with this as its only prototype part.
As for the hull reinforcement, I think it should be durantium and needs a stonger effect. Honestly trippling the effect to +75 HP would not be unreasonable.