We make the trip from FL to CA each year and pretty much stay in Passport America campgrounds. We only drive 250- to maybe 350 miles a day.
Since you are leaving Houston I-10, our next stop would be around San Antonio in either:
River Bend RV Park, PA rate: $15
1881 S State Hwy 80 , Luling, TX 78648 (830) 875-9548
or alternate:
Hill Country RV Resort, $21.00 - $23.50
131 Rueckle Road
New Braunfels TX, 78130 (830) 625-1919
Next stop would be:
Parkview RV Park, $11.00
Fort Stockton TX, 79735 (432) 336-7733
Next stop:
Coachlight RV Park , PA rate: $18.00
301 South Motel Blvd,
Las Cruces NM, 88007 (575) 526-3301
Next stop:
Ft Willcox RV Park PA rate: $14.00 - $15.00
1765 W Fort Willcox Loop (520) 384-4986
Willcox AZ, 85643
Next stop:
Saddle Mountain RV Park, $16.00
Tonopah AZ, (623) 386-3892
Next stop is in the Palm Springs area and we park in son's driveway out back.
Price is right.

I don't have an recommendations for the Pomona area as I have never stayed there.
If you are not familiar with PPA, you may want to look into it as you can save the price of the annual fee in the first few nights of camping. It does have its limitations, but easy to work around.
Have a great trip.