If you absolutely must splice, (which I don't recommend if you can avoid it) I would skive at least 3" on both sides, and add a liner if possible to strengthen it even more. then glue and stitch. A little hint on skiving long pieces for overlapp, use a belt sander or something similar, it takes some practice to not overdo it, but it works great, you can get a perfect taper up to about 8-10" if you want.
I have made both the threaded loop type and the stitched loop type, I prefer the threaded loops because they are adjustable, especially if it is a belt for something large like shotgun shells etc. Use a slot punch to cut the holes, for small caliber use one slot per cartridge and loop the leather strap out and back into the same hole. for large shells use two slots. Make the loops pretty tight, and the wet form them. good luck.