I used option 3 on Aldebaran V, 1995. No stringers, never had a problem.
Your option 3; 'new' top of foam must have a capping so the 'I' beam edge does not cut down into the foam. I used 3mm ply but glass resined onto the foam may also work. If you have the WRC stringers already, may be OK but is it necessary to have the 'I' beam full height? Why not have them (the stringer width of) 16mm lower and sit them ontop of the 'I' beam. Glue them onto the 'I' beam (during the application of the glass fabric), glue the stringers onto the 'I' beam, glue the deck onto the stringers, stringers will not move once the deck glue has grip of them also.
Hint, to shape the top of the 'I' beam:
1. cut to length (int. width of hull)
2. place a piece of 16mm timber ontop of the 'new' foam top
3. place the 'I' beam in position ontop of it
4. scribe the deck curvature onto it using a concaved deck curve template spanning across the gunwales
5. remove 'I' beam and cut to scribed line
6. remove 16mm spacer piece, glass, fit and glue shaped 'I' beam. (Devise a method to hold them vertical.)
7. glue stringers onto it.
This method will not need the tops of the 'I' beams to be shaped after fitting. The glued stringers will need only minimal truing.
Step 6 can be left until all items prepared and the gluing done in one application. Label parts for correct location when experiencing "gluing stress".
NB: ensure the new deck has 2 layers of epoxy applied to the under surface, 1st allowed to gel, 2nd applied during fitting.
Ensure the tops of the stringers are precoated also or they will 'suck' the glue mixture dry and weaken the glue bond.
Trust I am not teaching to 'suck eggs'.
Good luck with it all.