Hello Ed,
Tea towels will benefit from a light pre-treatment as they are constantly wet and get a lot of hammer a normal t-shirt would never see. I would also recommend a double cure with a few minutes breath time in between, let the tea towel cool down off the heat press (or out of the dryer) then cure it again. You will probably get the best results from the IA CMYK & light PT as the cure time is 40 seconds which should not be long enough to scorch the towel. All waterbed inks will fade eventually so the better the cure the longer it will last.
Hope this helps.
Colin