Our upholstery guys (SEANAE interiors) made us custom carpeting and it did not cost that much.
They used a carpet material that is laminated. That is to say.., the top surface carpet had zero backing, and the carpet backing is flexible.
They cut and fitted the backing, then spray glued the top on using a short cut pile.
Result is ZERO seams anywhere, and it looks fantastic.
And yes, we have an oversize tunnel, subframe connectors, and other protruding shapes.
See, SEANAE specializes in airplane and boat interiors which, apparently, replacement carpeting is not that available.
So, that may be an option for YOU.
What is the down side?
You have to vacuum this carpet once it's installed to get rid of the loose threads.
Also, we are located in central Missouri.., and so is SEANAE.