How are you? Please accept my humble greetings. I am skilled with eCommerce, HTML, Prestashop, Shopping Carts, Website Design.
Can you please tell me the 'very small task' that you want to apply onMais
I can understand what you need for your website. So here is the solution for your module.
I have already developed a one page checkout module in prestashop. You can see the same on given link: