I don't have any experience with OO.o automation either, but a relatively quick Googling came up with an example showing how to hide the application. I also came across a VBA example that might help (but I bet you've already found). The Win32::OLE for OO.o surely does seem very different from Excel (I've dabbbled with that myself, because at the time Win32::OLE was much faster than Spreadsheet::WriteExcel). Good luck with your project!

Aside: It won't help your project, but I came across an excellent presentation on translating VBA to Perl Win32::OLE. I wonder if that was done by Corion?