I have never smoked a rack of full spare ribs. ~20+ years.
I started my journey of smoking meats because of BB ribs to begin with.
Will occasionally smoke ST Louis cut, but will usually buy the thinnest BBs I can find.
I think I may be in the minority.
You should, or at least take those full spares and chop off the tips and smoke them separately. They make great eats. Applebee's made a franchise chain off their rib tips.
BTW, you are not in the minority with buying the thinnest BB's. That extra meat is off the dry as F*ck center cut loin. Try to avoid as much as that "extra meaty" as you can. I shoot for less then 2/lb racks.