Every archiver I've seen allows me to specify the temporary folder path; including Winrar. If they aren't specified, %temp% is used.
It seems that the unraring process for Newbin creates a .tmp folder near where it plans to extract the files. There are complications/issues in some cases because of this (fragmentation, performance, etc); which is why archivers allow for user-defined temp folders. In my case, I use a directory monitoring tool to monitor for newly downloaded media files. However, they unfortunately get created in a temporary folder first, then get moved to an adjacent folder. So, my directory monitoring tool runs twice, onces for the files in the tmp folder and once for the final folder. If they were created outside my newsbin downloads folder, I wouldn't have this problem.
Having said that, I found the "override UnRAR path" setting, however, it doesn't look like it's meant for the temp folder (*.tmp folder).