Initialise complex object

What options are available to create an object with lots of parameters in the global namespace? I'm thinking of the tradeoff between temporary object/variable creation and readability.

This is for embedded programming on the Arduino. It probably doesn't matter too much for what I am doing, but would like to know the best practices.

Feel free to constructively criticise my code!

The two options that I can think of are:

1. A constructor with lots of parameters.
2. A constructor with a single struct parameter.

Option 1 looks messy and hard to follow with lots of parameters.
Option 2 requires a temporary struct variable for readability.

Example below (normally I would separate into headers etc.):

#include <Arduino.h>
class NestedClass {
public:

  // Empty constructor for creation of unitialised object. Bad practice?
  NestedClass() {
  }

  // Main constructor.
  NestedClass(float voltageReference) :
      voltageReference_(voltageReference) { // Use initialisation list.
  }

  float measureVoltage(uint_fast8_t channel) {
    // Convert ADC value to absolute voltage.
    return analogRead(channel) * (voltageReference_ / 1024);
  }

private:
  float voltageReference_;
};

class ComplexClass {
public:

  enum class Mode
    : uint_fast8_t {
      MODE1,
    MODE2,
    MODE3
  };

  struct Parameters {
    uint_fast8_t parameter1;
    uint8_t parameter2;
    float parameter3;
    float parameter4;
    Mode mode;
    float voltageReference;
  };

  // Empty constructor for creation of unitialised object. Bad practice?
  ComplexClass(void) {
  }

  // Big constructor. Messy when used.
  ComplexClass(uint_fast8_t parameter1, uint8_t parameter2, float parameter3,
      float parameter4, Mode mode, float voltageReference) {
    // Could have used initialisation list instead.
    this->parameter1_ = parameter1;
    this->parameter2_ = parameter2;
    this->parameter3_ = parameter3;
    this->parameter4_ = parameter4;
    this->mode_ = mode;
    this->nestedClass_ = NestedClass(voltageReference); // Wasted temporary object with reassignment?
  }

  // Alternative constructor. Looks neater/more legible when used.
  ComplexClass(Parameters parameters) {
    this->parameter1_ = parameters.parameter1;
    this->parameter2_ = parameters.parameter2;
    this->parameter3_ = parameters.parameter3;
    this->parameter4_ = parameters.parameter4;
    this->mode_ = parameters.mode;
    this->nestedClass_ = NestedClass(parameters.voltageReference); // Wasted temporary object with reassignment?
  }

  void megaMeasurements() {
    // Do something involving nestedClass.measureVoltage().
  }

private:
  // Maybe put all of these in another struct for neatness?
  uint_fast8_t parameter1_;
  uint8_t parameter2_;
  float parameter3_;
  float parameter4_;
  Mode mode_;

  NestedClass nestedClass_;
};

//####################
// Start main code.
//####################

// Option 1:
// Not immediately obvious which value is for which parameter.
ComplexClass complexClass(1, 2, 3.30, 2.7, ComplexClass::Mode::MODE2, 5.00);

// Option 2:
// Unitialised object (sort-of).
ComplexClass complexClass2;

// Arduino standard function. Called once from main.cpp
void setup() {
  // Option 2 continued:
  ComplexClass::Parameters parameters;
  parameters.mode = ComplexClass::Mode::MODE2;
  parameters.parameter4 = 3.30;
  parameters.parameter1 = 1;
  parameters.parameter2 = 2;
  parameters.parameter3 = 3.30;
  parameters.parameter4 = 2.7;
  parameters.voltageReference = 5.00;
  complexClass2 = ComplexClass(parameters); // Reassignment. Wasteful?
}

// Arduino standard function. Called in a continuous loop after setup().
void loop() {
  complexClass.megaMeasurements();
  complexClass2.megaMeasurements();
}