I guess it all depends on your definition of "bombproof". That Keith brand stuff is known for being heavy made and the weight of just your bowl alone at 3.2 oz shows that. It may be difficult to come up with a lid as strong as the bowl itself,IMHO..
Your pot diameter is huge-7.2"?? So finding an existing lid is going to be pretty tough. I have two DIY suggestions. One heavier but stronger and multi-purpose .The other lighter, but more fragile.
The easiest and strongest would be simply buy a 7.5" diameter Snowpeak Ti Trek plate and use it as a combibation lid ,plate ,frying pan and frisbie?.. It will addabout 2 ounces as will be plenty strong and cheap at about $16.
A good Ti DIY lid solution would be to get a 8" x 8" square of .005" Ti foil and trace the bowl outline on the foil with a Sharpie marker. Then cut it out with shears along the outer edge of the circle. There should be enough to rest firmly on the pot rim. Then make a pair of 1/4" long slits spaced 3/4" apart at 3,6,9 & 12 o'clock around the edge and bend the tab formed between then down about 45 degrees. Those spacer tabs will keep the lid centered and on the pot. Put a self sticking Aluminium foil tab in the center as a lid lifter and maybe a vent hole and you are done. Finished weight should be about .75 oz.