Historical experiments with towed naval force multipliers

Have real navies used towed systems as force multipliers like Honor Harrington's missile pods?

Yes, but examples from torpedo boats to invasion barges show that extra payload comes with severe mobility and vulnerability penalties.

Russian torpedo boats towed toward Tsushima and barges used in amphibious assaults provide historical parallels to Honor Harrington's towed missile pods. Operation Sea Lion depended on large numbers of unpowered barges because Germany lacked enough engines, leaving slow convoys dependent on towlines. Torpedo-boat mothership experiments used another method: carrying boats close to a battle and lowering them by crane or davit. Japanese destroyers also carried and towed watertight supply containers toward Guadalcanal, releasing them near shore in the hope that momentum would carry them in; the attempt was not particularly successful. A German proposal placed a V-2 in a floating pod towed by a U-boat, then partially submerged the pod into an upright firing position for an attack on New York. These examples include supply operations and unrealized proposals as well as combat craft.