I, like Case, seldom trim my spare ribs. I realize you have extra thickness there but it matters if I am grilling yes, but when low and slow I have not had a problem. I am new to the Foiling type of cooking, but learning. My last spare ribs I did in an electric smoker 220, 3 2 1 and the bones were falling out as I tryed to pick 'em up. The last 1, is there to help dry 'em out a little and firm up the meat I believe. Also gives a handy time period for folks who like that sauce stuff.
Right now here its 25 degrees cooler outside than it was then, the house A/C now even turns off some during the day. So if your climate is nice it might be the perfect time to try 'em the regular 3 2 1 and find a good set point to build upon.
I sorta think that maybe 3 3 might give ya pulled pork spare ribs. But thats my opinion using my climate conditions.
If ya have room, its pretty nice to set a pan of beans under the ribs too! Mmmmm....gud!