Any way to grab struct from DLL using dlsym (Dynamic Linking) without header file (.h)?

I have been looking everywhere for this question, but I cannot seem to get the answer for this. So, every example I have been to is simply how to grab function pointers from SO file, which I have done. However, let just say I have this compiled as my .SO file:

(these codes compiled into libsampleso.so):

sampleso.hpp:

#IFNDEF SAMPLESO_HPP__
#DEFINE SAMPLESO_HPP__
struct carDescriptor
{
    const char* model;
    int prod_year;
    int wheel_num;
    const char* license_plate;
    const char* colour;
} car;

carDescriptor fillCarID(void);
#ENDIF

sampleso.cpp:

#include "sampleso.hpp"

//Struct car fillup function
carDescriptor fillCarID(void)
{
    car.model = "Ford Fiesta";
    car.prod_year = 2014;
    car.wheel_num = 4;
    car.colour = "Midnight Blue";
    car.license_plate = "D 1234 ABC";

    return car;
}

now, compiled, I've got these out of objdump -T libsampleso.so: car (the struct) and _Z9fillCarIDv (the function).

if the return value of _Z9fillCarIDv() (aka fillCarID()) is normal datatype (e.g. string or int), it's easy with dlsym. However, for this I need to cast the struct first and then the function. I've tried creating an empty struct, and then cast dlsym to it:

struct carDesc * cars;
cars = reinterpret_cast<struct carDesc*>(dlsym(hHandler,"car"));

but seems to be impossible to use that as the datatype for the function:

carDesc(*__fn_fillCarIDv)(void);
__fn_fillCarIDv = reinterpret_cast<carDesc(*)(void)>(dlsym(hHandler,"_Z9fillCarIDv"));

cars = __fn_fillCarIDv(); //doesn't work, error: function returns incomplete type "carDesc" C/C++(862)

Anyone ever tried to grab a struct using dlsym without .h file?

Also, how do you deal with the elements from the struct grabbed by dlsym? I know that you don't have the proper elements listed without .h file, and obviously some pointer shifting is necessary, but can anyone give me an example of how to do it?

Thanks