My roof aims a bit more east than yours does (maybe ENE) and I have a relatively good pitch where my panels are installed. My roof gets about 8 hours of sun a day during most of summer, a bit less at either side. I compensated by adding panels, I have 8 1/2 on my 2nd story roof (the 1/2 is because I had to block out some of the panel to allow it to go around my radon vent) and 5 panels on my 1st story garage roof for a total of about 720 sq ft. In early spring, I can add 8 degrees or so a day (when the water is cold), so I can normally get my pool to the high 70s, low 80s by late May / early June (in New York). Depending on the weather (rain is really the only factor, cloudy days still produce heat), I have kept my pool open with the water into the low 70s into November. We have had the pool into the low 90s (sort of as a test). So, it can definitely be done.
And, just for good measure, I have about a 130 foot underground (uninsulated) pipe run from the pump pad to the house (and back). Not ideal, but it still works quite well!
I did the installation in 2 steps, so it cost me more than if I had done it all at once. I added the 5 garage panels, not to get more heat but to get quicker recovery when the pool gets cooled down (again, almost exclusively by rain). I put the panels on the back roof to hide them from the street, if I had to do it all over again, I probably would put them in the front and wouldn't have needed the garage panels. I have had 7 years of a wonderful, warm pool that stays open way past when everyone else in the neighborhood has closed for the season, all for about $7000 (and hopefully many more years without further investment, knock on wood).
I use a solar cover every night to retain heat (makes a huge difference for my pool).
If your main goal is to add heat during the "normal" season, I think you can get it done with no problem. If you are looking to extend your swimming season, that might be more problematic since your sun exposure only gets worse at the beginning and end of the season.
I agree that racking the panels to make them flat or pointing south would help, but in Tucson, I would think almost any direction would work!!