This was an old-fashioned space western, riding the wide open spaces, rescuing feisty damsels, fist-fights at the drop of an insult.
It also has a great sense of humor. The main character—who tells the story in first-person—can’t get into a fist-fight without getting knocked out immediately. Their biggest problems aren’t the “invisible alien enemies” promised on the cover (who never show up as far as I can tell, but who knows, they are invisible). Their biggest problems are dealing with bureaucratic red tape spun by the bad guys.
The back cover says that this was “never before in book form”, which, combined with the episodic nature of the chapters, leads me to suspect it was originally published serially in an older science fiction mag. It’s definitely a fun read.