Simple Customization Script, has a data model that could be used to save / store the customizations (for a save game or persistent state) as well as a simple randomization system for picking random elements at startup. The 'mandatory' flag is there because it does a pre-check to see if an element from this particular category should even be used…

Customizer.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace PixelWizards.GameSystem.Controllers
{
    public class CharacterCustomization
    {
        public int curBackpack = 0;
        public int curBag = 0;
        public int curBodykit = 0;
        public int curGlasses = 0;
        public int curHair = 0;
        public int curHeaddress = 0;
        public int curHelmet = 0;
        public int curMask = 0;
        public int curPants = 0;
        public int curShirt = 0;
        public int curShoes = 0;
        public int curVest = 0;
    }

    [ExecuteInEditMode]
    public class Customizer : MonoBehaviour
    {
        public bool doRandomCustomization = false;
        public CharacterCustomization dataModel = new CharacterCustomization();

        public bool mandatoryBackpack = false;
        public List<GameObject> backpacks = new List<GameObject>();
        
        public bool mandatoryBag = false;
        public List<GameObject> bags = new List<GameObject>();
        
        public bool mandatoryBodykit = false;
        public List<GameObject> bodykit = new List<GameObject>();

        public bool mandatoryGlasses = false;
        public List<GameObject> glasses = new List<GameObject>();

        public bool mandatoryHair = false;
        public List<GameObject> hairstyles = new List<GameObject>();

        public bool mandatoryHeaddress = false;
        public List<GameObject> headdress = new List<GameObject>();

        public bool mandatoryHelmet = false;
        public List<GameObject> helmets = new List<GameObject>();

        public bool mandatoryMasks = false;
        public List<GameObject> masks = new List<GameObject>();

        public bool mandatoryPants = false;
        public List<GameObject> pants = new List<GameObject>();

        public bool mandatoryShirt = false;
        public List<GameObject> shirts = new List<GameObject>();

        public bool mandatoryShoes = false;
        public List<GameObject> shoes = new List<GameObject>();

        public bool mandatoryVest = false;
        public List<GameObject> vests = new List<GameObject>();

        // Use this for initialization
        private void Start()
        {
            if (doRandomCustomization)
                DoRandomizer();
        }



        public void DoRandomizer()
        {
            dataModel.curBackpack = RandomizeGroup(backpacks, mandatoryBackpack);
            dataModel.curBag = RandomizeGroup(bags, mandatoryBag);
            dataModel.curBodykit = RandomizeGroup(bodykit, mandatoryBodykit);
            dataModel.curGlasses = RandomizeGroup(glasses, mandatoryGlasses);
            dataModel.curHair = RandomizeGroup(hairstyles, mandatoryHair);
            dataModel.curHeaddress = RandomizeGroup(headdress, mandatoryHeaddress);
            dataModel.curHelmet = RandomizeGroup(helmets, mandatoryHelmet);
            dataModel.curMask = RandomizeGroup(masks, mandatoryMasks);
            dataModel.curPants = RandomizeGroup(pants, mandatoryPants);
            dataModel.curShirt = RandomizeGroup(shirts, mandatoryShirt);
            dataModel.curShoes = RandomizeGroup(shoes, mandatoryShoes);
            dataModel.curVest = RandomizeGroup(vests, mandatoryVest);
        }

        private int RandomizeGroup(List<GameObject> thisGroup, bool isMandatory)
        {
            int current = -1;
            if (thisGroup.Count > 0)
            {
                DisableAllInGroup(thisGroup);
                if ( isMandatory)
                {
                    current = DoRandomSingle(thisGroup);
                }
                else
                {
                    var useGroup = (UnityEngine.Random.Range(0, 100) > 50) ? true : false;
                    if (useGroup)
                    {
                        current = DoRandomSingle(thisGroup);
                    }
                    else
                    {
                        current = -1;
                    }
                }
            }
            return current;
        }

        private int DoRandomSingle( List<GameObject> thisGroup)
        {
            var current = UnityEngine.Random.Range(0, thisGroup.Count - 1);
            thisGroup[current].SetActive(true);
            return current;
        }

        private void DisableAllInGroup( List<GameObject> thisGroup)
        {
            foreach (var thisEntry in thisGroup)
            {
                thisEntry.SetActive(false);
            }
        }
    }
}