Refer to Act 1 Scene 2, lines 69-71. Here is my theory:
She moves me not, or not removes at least
Affection's edge in me, were she as rough
As the swelling Adriatic seas.
In terms of historical context, the Adriatic sea is the backyard of the Venetians and has been under the control of Venice ever since its rise. Noting the play's setting in Italy, and the word 'swelling' possibly being a euphemism for 'rise', could Venice be used as a metaphor for Petruchio's affection? This is because Venice conjures up a picturesque image, the water city that is both beautiful and unconventional for its success as a maritime empire. Both attributes can relate back to Katherina. In addition, 'not removes at least affection's edge...were she as rough' seems to suggest that he is undaunted by the feat to tame the Adriatic seas.
Is my theory too far fetched or are there any sort of basis for this?
One of the qualities of literary analysis is that it leaves room for the reader to make meaning and extrapolate from a writer's lines. When one is dealing with an author as thoroughly criticized and analyzed as William Shakespeare, uncovering some new meaning in a text can be quite a feat. Remember that you are taking what YOU see in the text and putting it to your own analysis and interpretation. Therefore, if you can make a case for what you see as being supported by the words, (and from outside critical sources as well) then you have a valid argument. You have begun to do this in your theory. You look at Shakespeare's lines and see the connection. It is all about making those connections. Now I would suggest that you look around for some solid scholarly criticism that might make your argument more robust.