If you can't see what is wrong with cheating to "protect" yourself then I don't know what to say. Why not use some tried and true methods of: offline play, boss fog walls, not reverse hallowing, or alt-f4ing from the game?
The reason people are awful at the game for using trainers is you are not taking the time to further your skill at an aspect of the game, or the whole game in general. Playing online carries a risk vs reward. If you think the risk is way too high for the reward, play offline. Or you can use the ZERO SKILL method of cheating your way to victory, degrading legitimate online players' experience.
Yeah, getting invaded is a harrowing experience the first couple times. However, if you die, so freaking what? Dying is what the game is about. Lose humanity? so what? Lose souls? SO WHAT? If you really cared about either of those things you would sit at an easy spot to be summoned (you don't need to reverse to be summoned) and just farm farm farm.
Whether you see it or not, trainers ruin the game. Period. End of story.