With the verticle bar broken you will likely need a complete ladder to make it safe again. It sounds like you could use a Surco # SP502L Universal Exterior Ladder to replace your broken one. This ladder measures 84-1/2" tall and will work on many motorhomes. If this is not a match for you, check out the links I provided below for other sizes and repair parts.
You might even want to consider a stand-alone collapsible ladder like the TeleSteps # TE64FR 12-1/2' ladder. view full answer...
The correct Roadmaster rear sway bar for your 2022 Tiffin Allegro Open Road 34PA with a 26k GVWR is the part # RM25VR. This works with your Liquid Spring suspension setup as well. view full answer...