1) take a piece of balsa wood and carve/sand a small base to the complimentary angle of the rear slope of the prism (thereby putting the top of the balsa base parallel with the world)
2) with ONE drop of CA glue, attach that block of balsa to the prism where the angle is correct
3) with ONE drop of CA, glue the shoe to the flat top of the block of balsa
4) test it, and if you like it, cut it off, clean off the balsa from both the prism and the shoe, and replace it with a piece of basswood or walnut or oak carved/sanded to the same angle
5) then do the same thing again only this time leave it on and use TWO drops of CA between the parts
6) Wein used to make a hot shoe with a ~12 inch PC cord; maybe they still do; I have one from years ago; its for safe use of high voltage strobes (i.e. Vivitar 285...) on low voltage camera bodies
7) with a strobe that is not too heavy it should work fine!
8) make sure to get some CA Debonder in case you want to take everything apart; the prism surface will come clean and no one will ever know the glue was there; youll need it for step 4 above anyway
9) if you wanted to get real fancy, you could take the oak model part to a machinist and have an aluminum part copied, then black anodize it and youd have a pro job!
10) if youve never worked with CA (cyanoacrylate) glue before, run plenty of tests before you do the final mating of parts; its marvelous stuff but dangerous if not handled correctly; your local hobby shop has a number of grades; get the slowest setting CA they have; it will set in 15-30 seconds giving you time to make sure things are just where you want them to be
Perry