Here's how to bring all of your existing settings over to a portable version of Reaper on Windows with OSARA and SWS included.
1. Use the Reaper installer to make a portable copy. Just check the
"Portable install" check box on the second screen of the installer,
then Shift+Tab back to the location field and set where you want it to
live.
2. Go to the Run dialog, type %appdata%, go to the Reaper folder
you'll find there and copy reaper.ini to your clipboard. This is the
file that contains your existing preferences from your normal static install.
3. Paste reaper.ini into the root of your new portable copy, replacing
the existing version that'll be there. That's all your prefs copied
over to the portable.
4. On the second screen of the OSARA installer, hit DownArrow once to
choose the "Portable installation" radio button. Hit next, and point
it to where your portable install of Reaper lives on the next screen.
5. On the second screen of the SWS installer, point it to the location
of your portable Reaper. This installer doesn't make any distinction
between static or portable installs. So long as the location is set
right, it'll do it's thing.

Oh and I perhaps should've said to start with, make sure Reaper isn't
running while you're going through those steps.

Once done, pop the portable folder you've made on a memory stick or similar, run reaper.exe inside that folder, and you should be in business.

Hope this is useful!