I never had such a problem so it's little bit hard for me to advise you something appropriate. I would try to use DLL with exportable function. In this DLL you should be able to get property (innerHTML) and you can make an array of chars. You can then write this array to file. If it works you could make custom VP. In custom VP you can compare two files.
The only one question is whether you are able to get this property (innerHTML), from your DLL using windows API or not.
You could go after the inner html of the child objects and place them into an array. That, or chhose a child object that contains the targeted html info. The 32k limit seems to be a hard limit. In some situations I am not able to get the full 32k, go figure.