You could always create a server on the same or another computer on your LAN using steamcmd, set sv_lan to 0 and copy the map to that (Your going to need to know how to port forward to get them to connect properly though, so google that up). However a word of warning if you do, if your internet sucks on upload and you didn't compress the size of the map, the testers you are going to ask to help are going to have to sit through a 5 min dl or so every time you make a significant change you want feedback on.
This does give you a free server independent of your tf2 window which would help should you need to join another server briefly as it wont close down the local server like it would when you use map <mapname>.