That bit about light models stalling easier is an interesting one. I suppose it's true but most of us don't fly models that light at the extreme where it's an issue. Also most such models have a low aspect ratio so the speed differential from inside to outside wing isn't that high. Adding dihedral also confuses the issue if the model is side slipping at all in the turn. Not sure how but I'm sure it would all have an effect.

Tip stallling the inside wing in a turn is a common thing to do on gliders with their higher aspect ratio wings that tend to be flown slowly. The higher span ratio increases the speed difference from the inside to outside wing and you set the stage for a tip stall. If just flying slowly isn't enough to do it then cranking in a whack of aileron with the low wing aileron going down and thus increasing the local angle of attack suddenly will certainly do the trick. The flat winged aileron birds are particularly suceptible to this where the poly ships don't seem to get it as badly. See my coments in the first paragraph for this bit.

Oddly enough we don't see that much about constant chord wings tip stalling. Without being able to test a model it's hard to say if they do tip stall consistently or if our choice of airfoils prevents it. Certainly it's possible to induce a tip stall with various control inputs but for a simple straight forward stall it may be that the constant chord wing lets go all at once. Certaily it's very close to all at once. Oddly enough this is one area where a person can do their own testing. Some thread tufts taped onto a wing and that wing attached to a boom that extends out from a car or truck far enough to avoid the bow wave could be remote controlled by the passenger to up the angle at various speeds until you see the heavy thread tufts start dancing about, lifting from the surface and even pulling forward. That's your stall. Doing such testing with existing wings on a stub fuselage at speeds of around 8 tp 20 mph depending on the model design would simulate the model landing and flaring to a stall. The 8 would be for a glider wing and the 20 for a sport power model. No damage would be done to the wing at that angle and speed but a lot of data on the stall progression could be had. The boom should probably extend out about 10 feet from the front bumper and hold the wing about 5 to 6 feet up to avoid, or at least minimize, any ground effect or bow wave off the vehicle. The angle of attack control could be a cable rig up or a control rod or whatever as long as it can move the model through a 10 to 15 degree angle and hold the settings at speed.

Tapered wings are another story. There's been lots of horror stories about highly tapered wings on scale models. P38's, DeHavilland Comets and a few others with high taper ratios are well known to require lots of washout or a fancy airfoil transition to avoid nasty tip stalling and rekitting.