Tiller to Pedestal Steering Conversion
With all due respect, there is no way in hell that I would ever suggest adding a wheel to a Beneteau First 235. These are really nice sailing boats that would absolutely be ruined by adding wheel steering. The cockpit is not configured for wheel steering so that anywhere you place a wheel your view of the headsails will be blocked or the cockpit will be encumbered. Adding a pedistal in the middle of a small cockpit will simply give you an obstacle to catch lines on, stumble around and trip over.
In a breeze, small better performing boats, like the 235, count on surgical steering and helm imput to keep the boat in balance and at speed. This is not a racing issue. This is a basic safety issue. Adding wheel steering to a boat this small would take away this critical ability.
Adding to the issues of adding wheel steering to a well balanced boat like the 235, is the really excessively bad idea of using a hydraulic system. Hydraulic systems are the system of last resort when a a boat gets too big, its rudder loads get to massive and its helm is remote from the rudder to permit any other system. These are almost no feel, high weight, high maintenance, high friction systems. They have no place on a boat with the kind of light helm of the 235. This goes far in excess of being a really bad idea.
If you need a place to "mount everything in and on" I would suggest that the aft bulkhead of the cabin would make a lot more sense. If you want to add a table a couple sockets in the cockpit sole would allow for removable table legs. But I can''t recommend stongly enough against adding wheel steering or a pedistal in the middle of the cockpit to a really wonderful little boat like the 235.