It is absolutely possible to only work (3) four day trips a month.
A few months ago I got a 24 and a 22 hour trip in my initial bid. I traded everything else away for a single 20 hour trip. That gave me 18 days off.
Later in the month, I accepted a junior man 2 day trip, which paid 14 hours.
So, I had 16 days off and credited 80.
The benefits of the SAP. It is the greatest QOL tool in the regionals.