I could sure use some ideas here!!! any advice??

Im going camping with my boyfriend and his kids this weekend, my mom doesnt like him due to the fact that he has kids (she is very traditional catholic hispanic and we are not married) so i dont really know how to let her know ill be out of town with out starting a war or the usual "your making the family look bad, running around like a tramp with some man and his kids" im well aware of the fact that im all grown and its my choice and im gonna go eitherway but i just dont want her to worry when i dont answer my phone so i think i should tell her. i just dont want to deal with the fight thats gonna happen as a result of telling her. any ideas??