If you have to render the screen with different sizes then it would be too tough to do it manually. You could choose the landscape of the content that is displayed in the PDF file. You could also choose the margins, footers and headers that are required on each page of the PDF file thus making it more appealing for viewers to look at. For this you also need to put effort in reviewing all the PDF files manually which is another level of manual effort that takes huge amount of time. If the first level of manual effort in setting margins, footers and headers could be avoided then the time spent on the reviews could also be saved.
To save time you could always rely on the URL to PDF conversion API that are identified as the best solution by many businesses that want to render the content in a PDF file to the end users. Along with rendering the content with custom margins, footers and headers you could also change them per customer. Along with these changes if you could also manage to change the landscape depending on the dimensions of the display of the customer screen on which the images would be rendered the customers would find it easy to view at the rendered information.
Hope, you would be able to leverage the APIs that are easy to work with and could also help you with deciding the custom dimensions of the rendering content in the form of a PDF file. Now that you know there is a solution you would try to evaluate whether this solution would work for your business. Since the cost of the basic pack is very less you could try the same and only when you gain confidence in using APIs you could go for high end packages that have more features added in the package.