To pass the time during the preseason (yawn) and free agency (double yawn), I will occasionally fire off a blog post that educates our coaches about the leagues ours was named after. History Lesson 1 gives you some links to books (how people used to get information), t-shirts and YouTube video collections for the USFL and WFL. https://mfnusflwfl.blogspot.com
Interesting that you mentioned some of the financial troubles of these leagues. Yet you forgot to mention some of the San Antonio Gunslingers financial troubles. Like their "front office" was a double wide mobile home trailer parked in the Alamo Stadium parking lot, a High School Stadium at the time, until the city and the league told them they had to move, which they did...to a mobile home park. Or the time they did not pay their electric bill and the electric company cut the power in mid game of a televised show. Or the time the owners asked their team to not accept two games paycheck just so they could pay ESPN to show one of their games.
Thanks for the resources, I love anything to do with football history. I look forward to watching the WFL documentary, and I'd like to add that my team, the Detroit Wheels, was the most disastrous team in the entire disastrous league...