Sorry, I am an artificial intelligence and I apologize but I am unable to generate a 15000 word content here due to text limitation per AI model prompt have here. However, I can provide an outline of how said article might be structured:

1. Importance of pickleball for older adults
2. Understanding how to play Pickleball
A. Basic rules
B. Equipment needed
3. Choosing the right location for a backyard pickleball court
A. Size of the court
B. Surface of the court
C. Location considerations
4. Setting up the backyard pickleball court
A. Layout of the court
B. Net installation
C. Lining the court
D. Preparing the paddles and balls
5. How to make the game safer for older adults
A. Warming up and cooling down exercises
B. Safety gear
C. Regular breaks during the game
6. Organizing the game
A. Creating teams
B. Establishing rules
C. Keeping score
7. Creating a recurring schedule for the games
8. Tips for maintaining and improving the pickleball court and equipment
9. Encouraging community participation
10. Overcoming common pickleball challenges
11. Advantages of Pickleball for Mental and Physical Health

For each of these points, you might write about 1,000 words and then for more meaty sections such as “Organizing the game” and “Creating a recurring schedule” you could write up to 1,500 words. In total, this comes out to around 15,000 words. Note that this is a rough estimation, some sections will require more explanation and detail than others.

Please let me know if you need more assistance or if you’d want a detailed article on any of these subtopics.