(Crossposting from the advice sub-forum, as I think I'll get more help here :P)
A month ago, my friends and I started running the Kingmaker adventure path. We were all very excited about the whole spirit of the adventure path: exploring a frontier, wilderness land and forging a kingdom there. I did make some changes to the adventure path: even though I still used Brevoy and the different names for locations and stuff, I didn't set it in Golarion and decided to use my own personal setting, which I wanted to make low/weird fantasy and gritty. Nothing against high fantasy, but I feel like my friends and I have grown closer to the sort of low-fantasy in the last few years.
My idea was to make it a world where civilization (Brevoy and other kingdoms) is low-fantasy: magic is something seen as dangerous and that drives you insane (the forces of Chaos, the Great Old Ones etc.) and besides the odd guy in the hut outside the village, no sane person dabbles in that. The only sentient race that people know of are humans, with a few dwarves considered a legacy from times past, but they live in the mountains in a secluded fashion so most people have never seen one. Religion is restricted to the only true faith, that of Treum, although there are struggles within his church and heresies sometimes sweep the land (think medieval Christendom). But as you step outside civilization, things become more weird fantasy, and you can encounter weird man-beasts, weird abominations and stuff like that.
So my idea was to make my characters as "plausible" as possible: no wizards or sorecerers as PCs, and clerics only able to cast spells that could be understood by someone in our Middle Ages (everyone could have faith in a cleric blessing you, not on casting a magical spirit light on your sword). This last point is a bit of contention with a player, but that's another story. At the same time, as the Stolen Lands are a frontier land, all of the things form the adventure path make sense in my setting, as they are "outside civilization" and thus do not clash with the feel. It only means that most people's reaction to seeing mites is not "hey that's a fey semihuman race maybe we can communicate" and more in the lines of "what is that abomination that looks like deformed human, kill it with fire".
My problem is: I know Pathfinder is a very magic-dependent system, but as I am an old school D&D fan and the adventure path is based on the Pathfinder ruleset, I did not mind trying my hand in it. Do you guys think it would require a lot of change? I'm asking because I'm new to Pathfinder and don't know if by restricting their magic casting and making magical items rarer I'm crippling them to the point where by the time they meet CR 7 encounters they will most likely die. Is it too difficult to run? What changes would you recommend? I've been looking into Iron Heroes. Would it fit the style I'm thinking of? I want clerics to have a certain role, but not with flashy spells. Would the conversion once we are already in level 2 be possible?
Keep in mind I don't have a problem with PCs facing fantastic elements, monsters, wizards, whatever. I probably was wrong in using "low-fantasy", as I was thinking more of "low-fantasy at home, in the civilized lands... once in the frontier, weird fantasy goes". So no problem with my PCs fighting trolls or lizardmen. I just want the stark contrast between human lands being devoid of that. That means that heroes don't trust wizards or magic as it's seen as a force of Chaos. Yeah, maybe once they get to know the weird hermit in the forest they might start to appreciate his skills and not want to burn him alive. But I don't want them thinking about magic as just another resource. It should be something dangerous, kind of like in the Middle Ages when monarchs had pagan wizards or psychics help them by trying to see the future: most people would be wary of such an idea, and it certainly would be kept from the general population as it would indicate that "something's off" with the king. I guess the correct term for the campaign I'm aiming for is Sword and Sorcery, a la a group of humans going into the lair of foul creatures and mad wizards and purging the land of those Chaos abominations. Think part Warhammer, part Conan.
So my problems would be more like "practical" difficulties when you bring low-fantasy heroes into weird fantasy territory. Are monsters going to be very difficult to hit and kill because PF assumes that characters will have access to magic buffs by that level? I think that's more or less solvable (bring down AC, bring down HP). The other problem, things like heroes being defenseless against relatively simple magic tricks because they don't use any magic, is more problematic. I'm thinking about a wizards controlling their mind easily, or simply levitating and them being unable to hit him. Or maybe a part of the AP where characters need a floating disk or a fly spell to cross over this huge chasm.
In order to solve the first problem, I was thinking of getting Iron Heroes. If I'm not wrong, it is a an add-on to 3.5 DnD where heroes can progress and become more powerful without the need of magic (extra feats, combat skills, etc.). Is anyone familiar with it? How difficult would it be to combine Iron Heroes PC´s with a Pathfinder AP as Kingmaker? (I mean, to have my PCs use IH classes etc but then monsters and enemies using magic and being straight out of the Kingmaker AP).
Thanks for all the help!