Just a note that Test Trak, Expedition Everest and RnRC all have single rider lines, so I wouldn't FP them.
Are you asking about FPs for him, for yourself, or for both of you to do together?
Because if he has FPs for Space Mtn, BTMRR, and Splash Mtn, you could try for FPs for yourself for easier rides like PP, IASW, WTP. Assuming he isn't interested in seeing them. Then you could both get 4th and subsequent FPs for rides you could do together, like Pirates, Buzz Light year and JC.
At the other parks I see more of a problem since there are fewer rides to choose from.
At Epcot he can ride TT single rider and FP Mission Space and Sum of All Thrills, leaving the 3rd FP for Soarin. You can FP Soarin for yourself, but there really aren't any attractions that you REALLY need a FP for that you can do. You may find yourself not using all of your FPs, or using them on something like a m&g.
At DHS I would think he'd do RnRC single rider and FP ToT, ST and TSM. You could FP TSM as well, but most of the other attractions really don't require FPs.
At AK, he can single rider EE and FP Dinosaur, Kali Rapids and KS. You would FP KS too (if you don't think it would be too bumpy for you), and maybe ITTBAB if he doesn't want to see it. This is one park where you might deliberately waste a FP so you could both try for the Lion King as your 4th.
Was this what you were contemplating, or am I misunderstanding your question?
One thing I will say- DD was there with her DH while pregnant, and the pregnancy + heat and humidity had her just seeking shade and a place to put her feet up while hubby got his thrills.