This is a pretty neat idear. What happens when the caliban is discovered in a populated area for isntance? Would this incur a big OCR bump? Would it be temporary, until they lurk again, or would it become something that is well known and eventually lead to an inability to hide their deformities? (I'm thinking like a fallen paladin) Basically, if the pc is careless, it'll eventually be well known what they are and they'll be ostricized.
Maybe the disguise skill could help with this though?
I think the disguise skill will be part and parcel to it. Could work out mechanically where a Caliban Lurk with the feat is able to use Human race for it's OCR rather than caliban but only while disguised.
I mean it could be thwarted by something as simple as a garda going “good check, domn” which would take the wind out of a characters sails through no fault of their own at like level 2. There are a lot of various different npcs with pretty high spot scores that I’m also unsure how feasible it would be for a low level to really adapt the concept without ignoring npcs. In Port they allow caliban some small measure of social acceptance if they keep covered but they also don’t want them just lingering with high society either. I only know of one exception and they’re a pc noble. Unless caliban go really out of their way to go above and beyond to be accepted into society, they know what they’re signing up for. Classes like sorcerer, favored soul, or bard (and warlock I suppose if they want a higher dc for their incantations) also wouldn’t feel much if any draw back in taking it.
Personally I think if you want to lean into that concept, disguise is a better and already established way to go about it. It is in essence what you want to achieve by pretending to be something they arent which is in this case normal. I played a high disguise character, it’s super fun, and you can always change it when you get discovered.
Context is everything. If your PC has a small vestigial tail hidden beneath heavy robes it's something that could reasonably missed during a search and couldn't simply be 'spotted'. Spot is just that. Spotting. It's not X-Ray vision.
That PC Noble isn't a caliban nor even in disguise.
Actually from an IC perspective no one signs up for anything they are simply born. On an OOC level I don't think it's at all avoiding what caliban players sign up for but instead embracing it and giving it a different perspective. Surely some of the less deformed caliban have thought "If I just do X they'd never know" instead of simply resigning themselves to the sewers or the woods. Caliban are generally undesired and unwanted. Some domains go as far as to drown them at birth. A good character motivation would be to try and ascertain precisely what they don't have; rather than simply not. People want most the very thing they can't/don't have.
The draw back is going any of those classes on Caliban in the first place... for the most part caliban and half orc are incredibly suboptimal. The +2 STR does not nearly weigh against -2 INT and -2 CHA. Sure many builds can ignore the CHA loss no problem, but the INT? That is crucial across the board. Not all classes require so much strength that it comes at the cost of 2 ability scores.
The 16 CHA would be the equivalent to another races 18 CHA. Most players espescially for some of the classes listed don't go to full max they go up to about 15 or so and then increase from there. A Caliban would have to invest so much more just to meet the human in those same classes. It's a harsh draw back; espescially since classes like Sorcerer don't usually use STR.
Disguise currently does not work because it is against the rules for one race to disguise as another. It also is foiled by WYSIWIG where someone can simply observe a character has the half orc model and then roll with that. My suggestion proposes an exception to that rule that comes with a cost, and addresses the issue with the model by having the feat unlocking access.