I can recommend the 15" 4:3 which has a ok quality display for non-moving graphics (the brand is Sharp): https://www.beetronics.be/ecran-15-pouces-en-metal-4-3

But beware, these are cheap Chinese monitors available from alibaba company jwell (cheaper but with bad display) so be prepared for a bad experience with the remote.

On the upside, these monitors have Composite (for use with older computers) and can be powered by 12v (span 9-33v, not tested though)!