Done some tests and stripping the audio is unlikely to save much space. This command will reduce the resolution down to 720 and strip the audio and use a pretty low bitrate. Should save some space. Obviously you can reduce the resolution further by changing "1280x720" to whatever you like. You can also change the bitrate by editing "-crf 30" to whatever you like. Higher crf = lower quality. (goes from 0-51 I believe).
 

ffmpeg -i whatever.mkv -an -vcodec libx264 -crf 30 -threads 0 -s 1280x720 whatever_smaller.mkv

Needs a version of ffpmeg with x264 support. I have no idea whether the default one on Windows has this but if not you can download one that does from here: https://ffmpeg.zeranoe.com/builds/ (may as well get the static builds to keep it simple).
 

Thanks babes, I appreciate you too.  I was just getting miffed with how long it seemed to take to upload a relatively small file to dropbox, so thought I could take a minute to save some upload time.  This is definitely turning out to be harder than I thought, so I'll just work on being patient.

<3