GCC - Struct defining members in specific offsets

Is there a way in gcc, where I could define a struct with a specific member in a specific offset?

I want to define a struct in the following way:

struct {
.offset(0xDC) //or something equivalent
   int bar;
} foo;

and then the following statement:

int a = foo.bar

will be identical to the statement:

int a = *(int*)((char*)&foo + 0xDC);

* UPDATE *

Some background: I want to access members in an exported struct which I have no proper definition, it has many members - which I care about only a handful of them, and their offset (the struct original definition) is a bit different on each target platform (I need to compile my code for a few different platforms)

I have considered the padding option mentioned on the comments here, but it requires me to do some annoying calculations each time I want to add a member. for example:

strcut {
.offset(0xDC)
    int bar;
.offset(0xF4)
    int moo;
}foo;

is simpler then:

struct __attribute__ ((__packed__)) struct {
   char pad1[0xD8];
   int bar;
   char pad2[0x18];
   int moo;
}foo;

and that without taking into consideration the fact the sizeof(int) can change from platform to platform