If you want rugged..go for the PA-31..as you already know from the Aztruck..parts when needed are pretty available..its an 8 seater (navajo) with heaps of excess capacity..and 175 kt..no worse than 310..probably reasonably priced..and with a set of vortex generators, gets off an 800m grass strip with the right technique
..and both aircraft have equally ridiculous fuel systems