Rails, use Carrierwave gem with not ActiveRecord

I have a Question model which was an ActiveRecord one, but I migrated it on Elasticsearch with Tire gem. Until it was on ActiveRecord everything was working great. But not anymore.

What I want is to upload a remote file (ex. : [URL visible pour les membres Pro]) and store the file name in "path" field on elasticsearch.

Here is my Question model (which currently doesn't work):
class Question
include ActiveModel::MassAssignmentSecurity
include ActiveModel::Validations
extend CarrierWave::Mount
include Tire::Model::Callbacks
include Tire::Model::Persistence

# set fields for carrierwave uploader
mount_uploader :path, QuestionUploader

validates_presence_of :question

attr_accessible :path
attr_accessor :remote_path_url, :remove_path

property :difficulty
property :question
property :path
end

And then in my questions_controller:

class QuestionsController < ApplicationController
def create
[Email visible pour les membres Pro] = Question.new question: "How are you ?", difficulty: 3
[Email visible pour les membres Pro] = "[URL visible pour les membres Pro]"
[Email visible pour les membres Pro]>

render nothing: true
end
end

Elasticsearch record works, but no upload happens...

What I'm waiting for this job is the question.rb questions_controller.rb and question_uploader.rb files

Requirement : Use Tire gem in PERSISTENCE mode ! And Carrierwave with Fog gem and S3 endpoint (but for development you can use local upload).

It's not a hard work then it's low budget. If you're able to make it work in a perfectly clean way (no workaround allowed) then you're my man!