In case this is not possible please you can help suggest extensions to create a custom checkout page or custom forms
The most generated errors being found on Opencart forum originates from contributed programming. The increased post counters are caused by redundancies of the same solutions that were already provided prior.
Opencart.com Administrator / Quality Assurance Analyst / Programmer
You can try OpenCart One Page Super Checkout Extension which simplifies the checkout process and incorporates the whole checkout process in a single page. You can even customize the layout of the checkout page.