Any Ideas on How to Protect an Air Mattress?

Yep,  plus one for the thinlite,  especially in terms of  sleeping pad protection.

25″ wide 1/4″ thick Polyethylene Foam, 80″ long, 7.43oz.

https://www.foamorder.com/foam/cross-poly-foam

1/8″ thick just didn’t do it for me; pine needles still poke through and kneeling on it still is just uncomfortable.  Goes between the ground and my bivy or Xmid.  Great for afternoon naps during breaks.

Have found that site selection and clearing only take a minute, and work with an adequate floor material to prevent damage to the sleeping pad.  However, a flimsy store bought pad or floor could create a different result.

Earlier on in this thread I mis-spoke (wrote). I wrote “And then I also use an 1/8th inch Evazote pad inside of my tent and beneath the bag.”  What I intended to say was, I use the thinlite pad beneath my inflatable mattress. to help prevent punctures.

Here’s a list of foam sources with weight, dimensions etc that I pulled together when looking for a mattress underpad, in this case to reduce noise.  Prices are Canadian

1/8″ EVA Foam Sources
byu/DDF750 inUltralightCanada

Gossamer Gear offers a rolled 59″ X 19″ evazote (2.7 oz) and a folding 73″ X 20″ (3.3 oz). Of course folding is better inside a pack unless you make a burrito out of it, and I find the 1/8″ foam doesn’t do well that way. Some may want the extra 14″ of the folding GG pad to protect the entire length of an air mat. It also provides more camp lounging comfort and a tad more backup in case inflatable goes flat.

MLD stocks a 40″ X 80″ evazote 1/8″ that allows you to cut a pad any size you want. Goes without saying a lot of people use 25″ to 30″ wide air mats and it will fit the bill. Ron also has the 1/8″ in 20″ X 40″ and 20″ X 60″. MLD 1/4″ thick evazote is available too….love the stuff. https://mountainlaureldesigns.com/product/goodnight-eva-1-8-foam-pad/

Confirmed. Folding 1/8” Evazote will create significant squared creases that will generally stay forever when placed in pack. Aside from not laying completely flat by itself because of, will not change its performance. The 1/8”, compared to the 1/4” & 1/2” generally speaking, likes to squirm, move and twist around to a certain extent anyways, due to the thinness. So either way, I tend to pack it whichever way is the most clever.