Yes, Toorak has it: X and LIP are the two kissers inside OS very large and an oxlip is a ‘bloomer’.
Splendiferous: anagram of fine, super, do and L which is the extreme of delightful.
Cryptomaniac: Close, but “anagram of fine, super, do and L” is only 12 letters. You need both extremes of ‘delightful’ — ‘D’ and ‘L’ — to get up to the required 13.
Unfortunately that gives you with two ‘D’s and only one ‘S’. Fortunately it turns out that the original clue has ‘so extremely’ rather than ‘do extremely’, which fixes that.