NetBSD won't run on an 8086, unfortunately, or on anything without an MMU and
(at least) 32 bit integers and addresses.  (More, of course, is fine.) The
phrase "those 8086 ISA DMA hacks" was a commentary about engineers designing,
in 1996, workstation-class 32-bit computers around a bus which was grossly
inadequate for a 16-bit processor in 1982...

A reasonable alternative to MS-DOS for the 8086 would be Minix.  Check out
the newsgroup comp.os.minix.