Traditional boxers are not designed for usage together with feminine period products. On the other hand, packing underwear can be suitable for pads. Try wearing tight briefs - the pad should fit tightly and securely. You can use boxers as well, although some models have too much free space. Emisil "Truhk" underwear is suitable for wearing period products since it is tight enough to support a pad and keep it in place while packing at the same time.