I find that a lot of PPL students are not used to crossing controls and this is partially due to the fact that slipping is not always taught extensively (check your POH for the limitations on this as well)
Yes, and a more basic reality is that most students have not included in their training, moving the flight controls to their extreme deflections in flight (not all at once, of course!). But pilots should be aware that the control deflection stops are set to be what you could need, but not more than needed. With planned and briefed maneuvering, it is practical to move each flight control to its maximum deflection, and certainly rudder and aileron, during a sideslip. All GA pilots should be comfortable sideslipping their certified planes, they will all do it fine. Yes, certain 172's have an "avoid" for slips with flaps extended, but it's not a prohibition, rather cautionary (so don't do it aggressively close to the ground). A type will not get certified if it cannot be safely sideslipped to maximum aileron and rudder deflection. I will regularly sideslip both my planes, particularly for precision during practiced forced approaches. If you're comfortable sideslipping, you'll find crosswind landings less worrisome.
instead of crabbing and applying rudder at the last moment, I let the student get into the 'one-wing-low' attitude
Yes, handle the dynamic crosswind landing situation with fewer "last minute" applying of different controls. Sure, you have fly the plane by controlling it, and that is naturally dynamic, but you don't need to make it more difficult on yourself by planning then timing last second drastic configuration changes. As much as conditions will allow, ease from one configuration to the next over many seconds, rather than trying to guess exactly the right second in which to drastically change things - while close to the ground. If you've been imperfect in aligning a tricycle plane with the runway centerline as the first main wheel touches, yes, plan to straighten it, but it will also tend to straighten itself. Touching the upwind mainwheel first will help this. (Taildraggers are something different!)
As said, practice, practice, practice! I know that when you finally get your hour after waiting for a few weeks to go flying, the last thought on your mind is to do circuits, but landings, takeoffs, maneuvering and practice emergencies require the most practice for currency, and seem to be practiced least during hundred dollar burger runs.