How do I handle hills with only 5 degrees of gun depression?

Try not to stop on the top of a ridge and expect to fight from there. Approach a shallow slope slowly, stop just before the crest, then edge forward only far enough to take a shot. That gives your gun a moment to settle and keeps you from exposing more of the hull than you need to. Dips, buildings, and other solid cover can be more useful than trying to make every hill work.

It helps to change the role you expect from each tank. The T-10 can move with faster allies and use openings rather than staying planted on a ridge. The IS-3 is often more comfortable working around buildings and corners. When using its pike-shaped front, face the threat fairly squarely instead of turning the hull sharply. You don't have to copy a hull-down style if the terrain doesn't suit it.