The Inogen One G3 mentioned above is one that a guy a few sites down from us winter before last had.
He used it both as a portable unit and also for night time use. It worked great, is much smaller than the big Invacare home unit my wife has and if we had continued full timing or snow birding we would have got one for her.
She just needs it at night but it is so much smaller that it could go in the bedroom instead of under the dinette like her Invacare unit. Not convenient under there and having to disconnect the hose and coil it up every morning was a pita.
You can see it
HERE