Lost my final aligners while waiting for refinements — what would you do?

I’m doing CandidPro and I’m currently waiting for my refinement trays.
I put my final set (#24) in on September 9 and wore them until September 29, so about 20 days total. I had already been scanned for refinements on September 22, and I was told the new trays would take about 2–4 weeks.
Unfortunately, I lost BOTH my upper and lower #24 trays. I also don’t have #23 anymore.
I contacted Candid and they told me everything has to go through my provider. My dental office told me I could use a moldable mouthguard temporarily while I wait. They didn’t specifically mention Instamorph; I found a video involving it myself.
My biggest concern is my teeth shifting enough that the refinements made from my September 22 scan won’t fit when they arrive.
Has anyone been in a similar situation where you lost your final trays after your refinement scan? How long were you without your aligners, did your teeth noticeably shift, and did your refinement trays still fit when they arrived?
Also, has anyone used a moldable mouthguard or Instamorph temporarily while waiting for replacement or refinement trays? How did that work out?