Chet, depending on the type of indoor/outdoor you have, you wouldn’t necessarily seam with heat tape, nor would you stretch it in; many of these floor coverings would be glued direct. Also, if you are not using a pad, you do not stretch in a carpet; it would be glued down.
Post back with some further detail on the carpeting for the appropriate installation/seaming methods; particularly whether the backing is a woven, scrim, or other type, and the type of surface yarn.