Hi amethyst.
I thought I'd take a wack at providing an updated version. It was easy enough to extract the pet, then delete /usr/local/bin/xdotool. [xdotool-64bit is already installed into my bionicpup64]. There was no /usr/lib/libxdo.so.? in the pet. [That library --and locations-- found on the xdotool pet I extracted before writing the prior post is likely later developments of xdotool]. Then repackaged it.
Installing and running the resulting pet opens 2 windows. But they are not side-by-side nor configured for immediate use.
MochiMoppel's suggestion "ROX SOAP script and a JWM Group setting" seemed the best way to create a pet sufficiently generalized that it could be used OOTB. But I couldn't find any information about how to set that up.
I then re-examined your suggestion, viewtopic.php?p=62854#p62854. It would be easy to include in a pet two empty folders --one / and the other /root-- and provide a command for rox to open those 'windows'. What would be needed is some way to configure their placement and size on any monitor*. Your script provides such specifics. But as you mentioned it was the result of testing on YOUR monitor. [A formula could likely be developed to ascertain the dimensions of the monitor and, using that and 0,0 as a starting point apply percentages rather than fixed points]. But I don't know where or how to include such configuration file in a pet.
As it now stands, rox-sets doesn't really make it that much easier to have two rox-windows than just starting rox twice, or starting rox once and right-clicking the up-Arrow.
* An application should be almost if not entirely usable OOTB. Configurations, if necessary, should be easy for even a newbie.