FWIW - I occasionally use something like Permatex Ultra-Black RTV - particularly if I need to build a little thickness. I’ve had good results.
There wouldn’t be anything wrong with that in your case, IMO. Super 300 is getting a little tough to source here in the States. RTV will be pretty awful to take apart if you or the next guy ever needs to.
I know several folks who really like “The Right Stuff.” I’ve just been too cheap to buy any up to this point.
