That should work as an interim solution. If you used thermal "paste" as opposed to "grease" you may not need either screws or ties. The paste is an epoxy that should hold the strips on its own.
Actually I don't recommend SolStrip DIY projects for "non-electronics technicians". That's why we offer complete kits and assembled units. Both the kits and the units include all of the proper hardware and instructions to build the intended lights. DIY is just that, "do it yourself". We have customers who build 25 strip mega-racks, and two-strip shelf and space bucket designs. We have folks building desert habitat lighting, reef tank and vivarium lighting, kitchen cabinet lighting, and laboratory bench lighting. Our designs are proven and broadly applicable to a wide range of uses.
Here's a snip of our X2 strip circuit design, showing the placement of the traces:
As you can see, there's quite a bit going on underneath the thin PCB mask layer. Keep in mind that in addition to routing power to the LED chips, the copper circuits perform a critical heat mitigation role by reducing resistance and providing a heat dispersion pathway from the chip to the aluminum backing and finally the heatsink. The answer to the question "how can we design the circuits to perform these dual roles better?" is simple: wider, thicker traces using more expensive copper. 2 oz. of copper to be exact.
Designs can always get better, but designs are always compromises between competing priorities. Thicker copper traces leave less room for large, reinforced bolt holes, which are entirely unnecessary to mount a 3.5 oz. LED strip. We've chosen superior circuit design, quality PCB construction, and superior LED components over bullet-proof mounting holes. Use the suggested mounting options: M3 nylon screws, or thermal tape, and none of these issues will arise. -b420