How to build a quick-and-easy wood ladder?
building a make-shift semi permanent  ladder is not a great idea for a couple of reasons.

First: It is very possible that your homeowner's insurance will insist it be removed or cancel your coverage.  I know this for fact as my insurance company (Good Neighbor) did an informal walk around my house and discovered a homemade ladder going from the sunroom roof up to the second floor roof. I had built it strong and attached it to a back wall in order to get up on the highest roof to remove snow. My agent called and explained the situation. a homemade ladder cannot be certified safe for a fire escape and by being permanently attached to the house invites unauthorized use and opens the Insurance company to liability.  Needless to say, they insisted I take it down.

Second reason: Although it may seem safe and secure at first, anything could happen. 2X4's as rungs could split. the angle may be bad and you might fall off.

Last reason: None of your friends here at SE want our favorite Yurt builder to get hurt.