The best you will probably get is by using the Wrap behaviour. You can read more about it here.
As for the seamless, no snap effect, I simply don't think it's possible, but I may be wrong.
I tried the behavior first thing, but as you mentioned it has a snapping effect.
I thought that I might be able to do some trickery with the scenery and specific teleport locations but it's not working out so well.
I could go the rotary route but that has it's own list of issues. :/