fusing plastic bags: can I use thicker &/or stiffer bags? Answered

I eat a lot of "pre-washed" & frozen produce, but those bags seem very different than the thin, almost filmy carriers, etc. I feel a little guilty throwng away these non-compostable bags (a few every week); but I'm also kind of scared of the fumes, so--rather than experiment blindly--would appreciate any guidance on whether this works, if you have experience with these other plastic types. Thanks!