Isn't this the very thickness that Warbonnetguy has recommended here or Brandon has recommended at his web page? Here it is from Brandon's Hammocks 101.
Lots of others prefer closed cell foam (ccf) pads which generally have a higher warmth-to-weight ratio although they are usually bulkier when packed, but tend to say put better in the hammock. These are available on the roll so you can buy what you need and then cut it to your desired width/shape. If the foam is high quality, 1/8" can be enough for summer nights, 1/4" thickness for milder weather (down into the 40's), 3/8" for cooler weather (to freezing or below) and 1/2"-5/8" down into the single digits and below. One example would be to have a 1/4" piece and a 3/8" piece. These could be used separately depending on the temps, and then could be stacked together to get 5/8" thickness for the coldest of weather. If you camp mostly in warmer weather, combining 1/8" and 1/4" might be a good option.
ccf is available at a reasonable price and by-the-yard at many upholstery shops. I've found very high quality foam on the A1 Foam and Fabrics Website. It is on a 60" roll, so be aware that you'll need 2 yards to get a 6' long piece.
The mini-cell foam here is about the same weight but seems like it might be slightly more warmth efficient, but at a bit higher price. I found the 1/16” mini-cell skins to be more like 1/8” thickness
Go to his web page to find links to URLS.