I noticed that movement combined with a balanced team really helped make higher hazard levels tolerable. For example, you can solo things a bit more on lower levels, but on higher levels having a good combination of crowd control (Driller excels in this) and single-point high DPS (such as the secondary with Engineer) makes it really balanced. We'd set up strats like Driller creating sticky flame traps all over to dump DPS downrange and soften targets while gunner can finish them off, or freeze targets allowing stuff like sentry guns to shatter them. It's really the team cohesion that makes hazard levels easier. When we paired our overclocks together in unique ways it made for easier play through (e.g. intentionally keep to flame or freezing, or, intentionally use both to leverage the temperature shock strat)