register a custom wrapper only with custom builder sub-class, not globally?

[Jonathan Rochkind]

I have a custom wrapper. 

I know I can register it globally with:

    config.wrappers :my_custom_wrapper etc. 

I also have a custom form builder (ie `class SomeCustomBuilder < SimpleForm::FormBuilder`)

Is there any way I can set things up so my :my_custom_wrapper is available for use with my SomeCustomBuilder, without actually registering it globally?

Thanks for any input, 

Jonathan