If you are comfortable with HTML, you can write your table using the HTML editing mode. Or, in your spreadsheet software you can save your spreadsheet table as a web page (HTML file). Then by looking at the html file you created in a text editor like notepad, you can copy everything between the
<table> </table> tags into your post. Of course you would have to be careful that your table width does not exceed the width of your post space, but the length of your table should not matter. I do notice that you have a nice looking table in your post on June 29, so perhaps you have figured it all out.