Its been a decade since I worked with atou (Almost TCP over UDP) but it does work: http://www.csm.ornl.gov/~dunigan/net100/atou.html
An excellent read on how to implement reliable UDP by Craig is here: https://pdfs.semanticscholar.org/1d88/1d58d53ee530a4b4c7427a...
Good chance they already did what you need. On supercomputers with a distributed filesystem (Sector/Sphere) at that. :)
Of course, you could use a userspace stack but you still have another problem: all the middleboxes between you can your destination. Anything that tries to be smart about your packets (NAT, proxies, younameit) may break your connectivity simply because it only understands TCP and UDP. I guess you could use UDP encapsulation but personally I'd start questioning whether picking SCTP as a transport protocol is worth all this trouble.
For a background on why TCP is this way, look up "The Design Philosophy of the DARPA Internet Protocols", by David D. Clark, however knowing is little comfort.