Designing with the GC out of mind

[JS]

I would like to remove the GC dependence on my own class objects 
I am designing and at some point remove the GC completely if 
possible(assuming at some point D itself will be GC agnostic).

1. Is there a way to determine what the GC is doing? I would like 
to know just how much my projects are GC depending(both for D 
internals and my code).

2. Have all classes implement an (almost final) interface to 
allow for custom allocation schemes. I suppose I can modify the 
sources, but is there an easier way? I don't want to have to 
implement the interface for every class I create nor explicitly 
specify the inheritance.

The interface here basically has a final New method and a virtual 
ClassSize method which gets the size of the class. (which I think 
is required over sizeof, classInstanceSize, etc... to prevent 
slicing). The ClassSize, while being virtual, is basically the 
same for every class(in fact it just returns a constant which is 
determined at compile time... I don't want the user to have to 
write the code for the class).