Combining Navmeshes for tiled terrains.

I have a 7x7 grid of terrain tiles, each with their own navmesh that I load additively into scene. (I load them like this because they are large areas - 4096x4096 with 2048 height mesh, with thousands of objects that are marked static - so baking would take forever/freeze and crash if I tried to do all at once, and scene becomes unworkable in editor)

What is the best way of combining these navmeshes? Is there a way of stitching their edges together? Can i use mesh.combinemesh?

I'd really rather not just use a whole bunch of offmesh links along the edges of the terrains as this is a really messy and not always workable solution.

EDIT: I've tried out 'navmesh link' from Github, and it's the best/easiest solution yet, but certainly not perfect - the 'jump' effect for one not being ideal. Surely there's a way to stitch together two navmeshes!?

Any suggestions would be MOST appreciated. Thanks in advance for any help!