roofing box profile

Fascia/soffit rotted away on a roof corner and collapsed ..... the fascia was fixed on 1 rafter tail only. the working space is only 230m wide/height to fix an extra support (a 2/4 with a 240mm torx) - "FIX 2" in the image.. impossible to drill into that space without removing any tiles or...

Hi guys. How do I finish off a box profile verge when I don't have a crown(high bit) to land it on. Cheers.