You could keep the glycerine warm. I do that with TEA in winter, as it freezes at about 70 F. I have what we call a brisker oven, used mainly for letting bread dough rise, that keeps a temperature around 100 F. I don't think glycerine is any less toxic than PEG, but it may have the advantage if you use USP glycerine in place of tech grade PEG. You can certainly try a small batch to see if the viscosity will be a problem for you. That would be the only reason for not using it.