Welcome Boldie24. I can't answer your question on how many panels will fit, but I will give you a link to read about mixing solar panels: https://solarpanelsvenue.com/mixing-solar-panels/
Its important to carefully match the voltage and amps on any mixed panels to avoid potentially significant losses to charging capabilities. I have mixed panels on my 27' Airstream and found panels that were closely matched to maximize charging potential. https://www.airforums.com/forums/f44...ml#post2288336
I'll bet Waninae39 will be along to answer your specific question about solar on a 22' Airstream. I think he has found a solution to maximize solar on his 22'.
2018 GT27Q, 73 nights 12,177 miles, 600W Solar - 110kWh, PD4655L, 6V Batteries, Blue Ox, 16" tires, 2019 F250 PSD
Sold: 2017 FC25FB, 316 nights 40,150 miles, Propride, 400W Solar - 200kWh in 216 days
2013 Casita SD17 89 nights 16,200 miles