How do I adjust the temp to bake country ribs so they take twice as long?
I don't consider this a complete answer, but I've been told enough times to stop putting potential answers in comments ... so ...

Temperature / time curves are so strange for meats that I find it easiest to look at a whole bunch of recipes, and find the one(s) that match the time I'm looking for, and then average the temperatures from those.

To expand that comment into a real answer, for this particular case, allrecipes.com gives 41 recipes when searching for 'pork country ribs'.  I then weeded out those without temperatures (stovetop, grill, slow cooker), or that weren't actually country rib recipes, leaving me with:


250°F : 2 hrs, drain fat &amp; liquid, coat w/ sauce, another 1hr
300°F : flour &amp; brown on all sides, bake ribs in sauce for 1.5hrs, turn over, another 1.5hrs.  (problem: calls for basting 'several times', which  slows things down)
325°F : simmering for 10 minutes, bake for 1.5hrs 
325°F : 1 to 1.5 hrs (until 160°F/70°C)
350°F : 1 hr, add sauce, another 1hr
350°F : grill for 12 minutes, bake for 1hr, add sauce, bake another 1.5 hrs.
350°F : 2 hrs
400°F : 1 hr


Slow cooker, just for comparison:


low :


6hrs ('asian style', so I assume wouldn't be 'fall off the bone')
7 to 9hrs
'about 8 hours' (until tender)
4hrs, add sauce, another 4 hrs
9hrs, straight from the fridge
8 to 10 hrs 'til falling apart (x2)
3 hrs  (major outlier)

high, then low:


1hr high, 8-9 hrs low.



...

So um ... wow, that wasn't useful.  I likely should've made sure if they were bone-in vs. boneless.  And it's possible those baked w/out sauce would have less insulation and cook faster.

Looking at more recipes isn't making it any clearer, but I'd have to say 225 to 250°F to get it take 4 hrs -- warm enough to dissolve the collagen, but low enough to make it take a while to overcook.