I haven't gotten here yet with my project, but have been thinking
about it.  I thought the most logical way to maximize toe space and to
still be able to keep the planned slide plate was to start with the
plate and work backwards.  IOW, take the rudder mounting (slide) plate
and support it temporarily with wood blocks into a level position.
Verify its range of motion (and subsequent rudder position adjustment)
before intstalling the actual subfloor.  Once you've got it in the position
that provides you with the most toe space and adequate fore/aft
location, use a straight edge to scribe its upper surface to the fuselage
wall and the nose gear tunnel.  Use a bullseye level to maintain the
level of the plate during adjustments.  Drop down from the scribed lines
an amount equal to the combined thickness of the slide plate and the sub-
floor and you'll have the upper location of the subfloor support blocks.

Remember, that unless you're a really long legged person, you'll probably
need to have the rudders located somewhere aft of their forward stop.
Short pilots can always be moved forward in the seat with the use of
additional cushions to provide reach JIC the full aft adjustment isn't
enough for them to get full rudder deflection and proper actuation of
the toe brakes.

Just some random thoughts.   <Marv>