What is the best harness to use with a 'strapless' double dildo?

Double dildos can be a bit daunting, especially because they are so frequently referred to as "strapless", implying that they are to be used without a harness. While that is possible, double dildos are designed with a bulb end that penetrates the wearer as well as the phallus, or what we would typically picture as the dildo to penetrate their partner. That takes a lot of strength, practice, dexterity and, frankly, is just a lot more challenging.