Word-counting in a subtree

[Jacopo De Simoi <wilderkde@gmail.com>]

tl;dr 

Is there a way to create a token on a subtree header that would count words in 
the subtree and [optionally] mark a maximum allowed number of words?

Long question

I am preparing an application and filling out many forms; each section of the 
form (that I rewrote as a subtree-header) has a maximum number of allowed 
words. 
It would be nice to have some kind of token to add to the subtree header which 
would count the number of words in the corresponding paragraph in a semi-
automatic way.  
As a bonus, one could also set a maximum number of words, and the token would 
switch to alert face when the maximum is reached. 

Is there a reasonable way to accomplish this? 

Thanks
 __J