I see two issues.
1) walk on roof - I have a manual that says my model has a walk on roof. I have been up there a number of times with no apparent problem. Do they address that point in your owner's manual?
2) Mine came with no ladder with no mention of one in the manual.. Other posts I've read seem to indicate that when a ladder comes standard, the frame at the attachment points is reinforced to support the ladder. So I would check with the manufacturer to see if that was an option for your RV and If so, where could/should it be attached.
Ladders also represent a temptation for local kids to try out and could be a potential liability.
Just my $.02
Safe travels and all the best.