Tricycle undercarriage has been offered on most off the latter Kitfoxes - it has never been approved in the UK so that would be something of a challenge.
The owner of the first mk 7 spent a fair bit of time with the PFA as it was trying to get the 1550 gross - no deal. It has subsequently been exported to New Zealand.
'Losing' 65kg is actually a massive challenge - it simply cannot be done and still have a complete aircraft.... The difficulty is that a Mk5 or later has a heavier airframe and so in most cases less payload than the earlier ones - unless it has a 912S. Unfortunately if it has the 912S, then it could usefully use another 25hp to cope with the gross weight....