If you're doing hand soldering with an iron, you should only be making contact (and potentially warming the surrounding components) for about 3 seconds. Only the point of contact with the tip of your iron should be reaching temperatures of any concern. Assuming the components you're worried about are also soldered in, there should be no issue or need for further precaution. They can clearly take full solder temp for a few seconds so a brief rise in ambient temperature will be nothing.
Aluminum foil is a marginally useful trick for creating a heat shield when doing hot air rework. You still want to keep it off the components you're trying to protect as much as possible. It should only serve to divert the hot air since it still conducts heat.
Kapton tape's virtue is that it doesn't break down under high temp, and it's available in anti-static formulations. It's great for holding things in place as you solder them, or maybe for holding down the aluminum foil as you do your hot air rework. Borderline useless for heat protection by itself though.