Challenge completed - 388 reps:

legs

• 12+12+12 squats s1:12kg, s2:14kg, s3:16kg (36)
• 8+10+8 bulgarian split squat (all sets: 16kg) (26)
• 12+12+12 leg curls (increasing weight) (36)
• 1min + 45sec Wall sit (20)

core

• Core superset (2 exercises) 12+15 per set, 3 sets (81)
• 12x3 Reverse crunches (36)
• 15x3 Same as reverse crunch, but "scissoring" legs (45)
• 8x30 sec planks without breaks (4 minutes planking = 12*4 = 48)
• 20x3 boat dumbbell raises and side to side (60)

Edit: Goodness, I finally reached 10k reps!!