Just wondering as a few have the HL mat with the R 3.3 value, what is the lowest temp you feel comfortable using this mat? Might you give me a general idea of the coldest conditions you have used it please - assuming you had the usual other adequate conditions in place correct bag/quilt, eaten well etc. Plus are there methods you've found worked to boost it for about the 100gms rather than something bulky like a 10mm CCF to boost it? The radiator reflector/picnic mat type stuff? Thanks kindly.