Can I reproduce video in 1440×1080 12M MP4 on a Full HD TV?
You don't mention either how (or IF?) you are editing anything here, or what forms of storage, distribution, archiving, etc you anticipate?

You are probably correct that MP4 is a more compatible distribution format, but distribution format does not necessarily have to be identical with recording and editing format.

I would not anticipate any issue with displaying a 1440×1080 frame on a 1920x1080 screen. Modern digital displays typically handle scaling (UP or DOWN) pretty seamlessly.  In any case, shouldn't it be easy to actually try it for yourself?  No amount of anonymous advice from the internet beats actual first-hand experiment.