The problem with duct tape and hose clamps is that the light is attached, which is off-topic. The OP has lights mounted on his long guns, already.
FWIW, Surefire makes, or did make, a high-end ($$$$) Weaponlight with a main light in line with the bore, but with one or more supplemental, dimmer LED lights for navigation and general illumination purposes. This might be what some folks would find ideal, though one had best be wealthy to buy into that concept. This unit mounts to a Picattinny rail, and has a vertical grip. The size and vertical grip prevented me from being interested; I want my SD/HD/duty shotgun to be light and agile, not a cumbersome burden.
When my chief decided to prohibit weapon-mounted lights on our weapons in 2007, I was, at first, angry and disgusted. (We purchase our own duty firearms, within guidelines; the common practice in this region.) But when I removed the Surefire integral weaponlight forend from my 870P, and installed a nicely slim Speedfeed LE forend, I soon discovered that the newer generation of extremely powerful yet slim hand-held lights made it quite reasonable to handle the shotgun and unattached light quite handily.