I use wood chocks made by a 4x6 cut into a curve to match the tire diameter. I used to use the cheap yellow plastic chocks but was never satisfied. While the plastic chocks are indeed light. They also do not handle you forgetting to remove them before pulling away. The wood chocks absolutely will not let you forget they are in place.
I have looked at the Harbor Freight rubber chocks but they are too narrow and I agree they smell awful. I think it was the smell more than the shape that made me reject them. I think I pictured the manufacturer using the wheel chock formula to dispose of toxic industrial waste. I know it's ridiculous, but I couldn't get over the smell.
You should always chock both the front and rear on both sides of the trailer.