Hi,
I'll be pleased to complete this project for you. Let me introduce myself: I'm a CCIE (R&S) certified network and systems specialist with 7+ years of experience in developing, configuring, securing and maintaining complex networks for large enterprises.
I'm passionate about Mikrotik and have extensive hands-on experience with all the features that you require on Mikrotik including load balancing, hotspot and captive portal. Here are some Mikrotik captive portal projects that I've done on Freelancer:
https://www.freelancer.com/projects/graphic-design/Develop-wifi-captive-portal-for/?w=f
https://www.freelancer.com/projects/graphic-design/Social-media-integration-wifi-captive/?w=f
https://www.freelancer.com/projects/graphic-design/create-customizable-Wifi-landing-page/?w=f
https://www.freelancer.com/projects/php/Mikrotik-router-captive-portal/?w=f
Please send me a message so that we may discuss this further. I can send you screenshots of my captive portals as well as their videos.