I think some people can get away with doing a rollerset and a light blow out or one pass of the flat iron. Basically let the rollerset "stretch" the hair. Just an idea.
When I was natural I got heat damage on my ends. But the stylist gave me that fresh relaxer look with her press. It looked good but I got split ends and she ended burning off parts of my hair
But I would suggest not going for that bone straight look because that requires more heat and a higher chance of heat damage. Try aiming for that "texlaxed" look.