@ISIWARE No, unfortunately, there is no way to show/hide headers footers upon exporting document to Html Fixed. However, you can decrease spacing between the pages by setting HtmlFixedSaveOptions.PageMargins property:
Document doc = new Document(@"C:\Temp\in.docx");
HtmlFixedSaveOptions opt = new HtmlFixedSaveOptions();
opt.PageMargins = 0;
doc.Save(@"C:\Temp\out.html", opt);
@ISIWARE I have logged a feature request WORDSNET-24543 about this. We will consider adding such option, but currently I cannot provide you any estimates or promises.
@ISIWARE Unfortunately, implementation of this feature has been postponed and is not yet scheduled for development. Please accept our apologies for your inconvenience.