Some samples of the code follows.

Sender:

RS485_Serial bus;
void loop ()
{
  Random r(1); //targeting device 1 in the bus
  if (r.request(bus)) { blink(r.val); } //make a request for a random number
                                        //blink the led the given number of times

  delay(1000);
}

Receiver:

RS485_Serial bus;
bus.set_address(1);
void loop ()
{
  listen(bus);
} 

Selected common parts:

struct Action {
  byte target_address;

  Action(byte addr): target_address(addr) {}
  virtual ~Action() {}

  virtual size_t size() const { return sizeof(*this); }
  virtual int  vrequest(RS485_Serial &) = 0;
  virtual void vrespond(RS485_Serial &) = 0;

  int request(RS485_Serial & bus) {
    bus.write(reinterpret_cast<byte*>(this), size());
    return vrequest(bus);
  }
  void respond(RS485_Serial & bus) {
    vrespond(bus); // <--- This virtual call makes the sender reset
  }
};

struct Random: Action {
  size_t size() const override { return sizeof(*this); }
  int val;
  Random(byte address): Action(address) {}

  int vrequest(RS485_Serial & bus) override {
    return bus.read(val);
  }
  void vrespond(RS485_Serial & bus) override {
    bus.write(static_cast<decltype(val)>(random(2,5)));
  }
};

void listen(RS485_Serial & bus) {
  byte * data = nullptr;
  byte length = 0;
  if ( bus.read(data, length) ){
    Action & a = *(reinterpret_cast<Action*>(data));
    if (a.size() == length) blink(3);
    if (a.target_address == bus.address) {
      a.respond(bus);
      //static_cast<Random*>(&a)->vrespond(); works but it has no point
    }
  }
}

My doubt is that if the vtable is stored in different positions, than the vtable pointer in the object obtained by the receiver will be off, causing the crash.