I do like limericks and when I took the time to read about the form what I commonly found were descriptions like "usually", "sometimes", "often" etc. The most profound statement I found was one lauding the limerick for it's inventiveness. Limericks not only allow deviation, they encourage it! It is even acceptable to INVENT a matching word if none exist by using part of the word you emulate, a sound that's needed or a comedic inference which will almost certainly be readily recognizable. Most places syllable count is secondary to rhythm.
Your examples are good contradictions
They scoff at the usual restrictions
Now amply discussed
You chuckle nonplussed
And deny us our dower addictions ...
... naughty girl
'rum