I consider this idea a good one, but missions against nomads should be even harder than against GRN, and trust me, the GRN missions are very awful... => You could not farm nomads when making missions since missions would have a difficulty ranking...
Have you ever fought a Wilde NPC? Even though in VHFs I swear they have the same hull as a high end GB. They are not easy to defeat in the slightest. Tougher then those Corsair Titans in the deep Omegas.