You can't get CAT2 on Rwy 26. Not now or ever unfortunately. For a CAT2 approach you need terra firma under you are 100ft RA. The lighting is the same for CAT2 and CAT3 but you need solid ground under you at 50ft RA for CAT3. Add to this you need to add 300m landing distance on top of your normal one for an autoland.
If you were to displace the threshold on 26 to allow the 100ft point to be on the starter strip, plus add 300m on the end, you'll be halfway to Castletown football pitch. For a CAT3A or 3B, you still need all the lighting and 300m extension but can get away with swinging some of the lights out on a gantry.
Both would also allow the 08 Localiser aerial to sit on the sea wall at the start of 26 though.
In practical terms, would they want to lose the New Castletown Road, or build a tunnel under it for traffic? For the 10 days a year we lose due to poor weather? I don't think the maths adds up my self.
I am all up for pushing the 26 threshold 60m towards Castletown where it used to be to allow more lighting and a reduction in CAT1 minima though.
The previous Airport Director was warned (minuted)not to move the GP antenna and threshold towards the sea to gain distance at the expense of lighting. She ignored the professional opinions at the time and feigned ignorance for many years afterwards.