They work good, really good, just be sure to drill and put a long bolt through the inside of the outside four corners - - that way you're not relying on allen scews to keep the frame from "spreading out" side to side. If you secure it side-to-side that way, then it won't come apart front-to-back either, coz the "90 degree L" at each corner keeps it all together. Then your cross bars - - and I'd go with 3 of those, to make a 4-bay frame out of it, i.e., 1 bay rower sits on, and put anything you want there, drybox, cooler, drop-bag with lid, 1 bay for rower's legs, and don't make this any bigger than it needs to be, 2 more bays for anything you want, i.e., dry, cooler, drop bag, in any order, although drybox in the middle seems to work good, yadayadayada!
Yeah! I like the Holleander Speed-Rail frames! Totally "customizable!"