What should I prepare for my second Mae Sai border run this Sunday in Thailand?

Hello Folks,

Looking to do a second Mae Sai Border Run this Sunday. Seeking some feedback and experience.

1. March - visited Phuket via flight for a short stay and left to Cambodia.

2. May 7 - flew into Chiang Mai (30 days stamp)

3. June 6 - first border run at Mae Sai (30 days)

4. July 5 - extended at Chiang Mai immigration (30 days)

Aware that there are two border crossings permitted per year. I don’t plan on staying in Thailand for too long. Currently at a retreat and plan to “check out” and leave around Aug 20th. If I knew my stay would be this long intially, would’ve just applied for a proper visa at Thai embassy.

What can I prepare for to minimize any issues at the second border crossing come this Sunday?

a. Bring paperwork from the retreat

b. Grab 20,000B in cash

c. Have a return flight?

Thank you in advance, wonderful people 🙏