So if you cast wind wall INTO the area of a cloud, does it effectively create an area that the cloud now cannot enter? Like you could cut a stinking cloud in half? Does this spell work on obscuring mist?
If you can influence some humanoids with money / religion / whatever, then all the better.
If that works, I hope you have a cleric amongst your rank of leaders. Have your bands of humanoids raid crypts for corpses, and animate them as undead. Even if you go beyond the limit of how many you can conrol, who cares - set them loose around your place as a buffer, or in any other spot you just want dangerous critters lurking. Animals might also be caught in traps (like bears/wolves) and turned undead.
Similarly, try to grab any and all local critters that you can to help buffer the area. Ogres/trolls/oozes if you can get them would make great allies/guards.
Start a plague and offer up the cure to plague, after you off any locals that can otherwise cure it, in exchange for what you need.