A good home workout for the legs. No weights needed, but if you do have some that will add to the difficulty. Recoveries around 30-60s. If time is limited then combined two exercises together. So whilst recovering from squats for example you could be doing your calf raises. This could save you as much as 15 mins.

If you have an accurate heart rate, then use that as your main data to determine pace, if not RPE is the best option. Hills are always going to cause them to go too high, unless you are super fit. Finish off with some strides.