Yep band clamps, U clamps deform and often split the flex tube resulting in leaks to total failure.
You cannot crush this stuff forever so the chicken way around running the flex tube is to keep a bunch of dog food cans around to make shims between the flies and hard tube if the gaps are wider than a slip fit. Connections for flex to flex requires a piece of hard tube, you cannot clamp flex to another flex with any kind of lasting results.
Needless to say flex really lowers flow as it generates a lot of turbulence. From a performance stand point it is not a good solution. Pre bent hard pipe even with a lot of clamps is a better solution if you can get the angles you need.
Developing welding skills is a life long investment in yourself, I highly recommend learning how and investing in the equipment. Harbor Freight is a good source of reasonably priced equipment for the hobbyist to moderate shop work in oxy/acetylene through various forms of electric. In my experience oxy/acetylene is the most flexible and simplest system to learn for the hobbyist It covers the needs of cutting, localized heating, and welding in one piece of equipment.