On normal, with U premove:
D' // pair (1/2)
U R U2 // 2x2x2 + pair (3/5)
F' U F U' // 2xcross + pair (4/9)
D' R' D R // uh... tripod? (4/13)
R2 F' R' F R F' R' F R' // AB2C, cancels 1 (8/21)
Skeleton:
+ D' U R U2 F' U F * U' D' R' D R' F' R F R F' R' F R' U
*: F' U' F D2 F' U F D2 // cancels 7 (1/22)
+: L U2 L' D' L U2 L' D // cancels 2 (6/28)
I also had found the continuation R F' R F R2 after the tripod, for 17 to 4 corners, by around the 20-minute mark. However, due to my inexperience with 2+2 cycles, I quickly got lost in finding insertions, so I decided to play it safe with about 25 minutes left, and did the 2-twisted insertion first, going back later to see if there was anything that immediately stood out in the 4C case. I didn't find anything quickly, so I just stuck with the 28. IF told me that the 4C was 27 optimal, and I did mine optimally, so I'm not too sad with my decision

I should work on 4C, 'tho...