The one on it is 18'. That's pretty big!
But I do look at my trailer too and wish it was longer to cover the bathroom door.
I think if you go much longer than 18' you will need a center arm.
2015 Jayflight SLX 287BHSW
2002 F-250 Extended Cab 4x4 6.8
Teconsha Prodigy P3 Brake Controller
Reese SC Weight Distrubition with sway control (12,000lb)