New user, Single Cycle wave creation

First of all, I was floored by how easy and fast the workfow is with Wavelab, and it instantly became an insta-buy as it made working with samples so much faster for me.
I don’t really use it for mastering yet, but mainly for editing samples for making either looping synth samples for some of my synths, as well as, and this is the key point for this entire post… single cycle wave files.

One of my synths allows for user single cycle wave files to use as oscillators and I was hoping to set up a nice way of doing this in wavelab pro.

There are a few key points in doing this that I need to do, and I can do them in wavelab, but I feel like I’m missing out on the know-how to do it more efficiently.
Key points:
File format is raw headerless 16 bit 44.1k files that are 4096 samples in length.
Must snap to zero at start and end for a smoothly looping sample.
Sample must be resized/stretched to be exactly 4096 samples.

Filename must export with the extension of .ws6 (seems easy enough to set up a preset for)

Firstly, the file format - Exporting to this seems fine, and batch processing can solve it. But I noticed I can’t seem to open the .ws6 files unless I rename them to .raw or such. Is there a way to add custom file extensions? Ideally I’d like to tell wavelab that any file with the .ws6 extension should be treated as a .raw as a 16-bit file with 44.1k sample rate. It’s not a dealbreaker, but it’d be nice to be able to import them directly without changing the extension.

Second, as far as I gather, I can only snap to zero crossings in the audio editor, and not in audio montage? Not a big deal, but it’d be nice to be able to do what I need in one view. Am I missing anything? Or should I use montage, and then just click the edit in audio editor?

As a follow up to that, I can’t seem to get audio stretching to work with these short sample files in the audio editor? I tried loading up a sample file of something like 800 or so samples, and stretching it to 4096, but nothing happens when I try this. It works if I try to stretch to longer lengths, in the second ranges or so. Is that a limitation?
In audio montage I noticed I could stretch the clips just fine, but I didn’t find a way to select a clip and stretch it to an arbitrary length. I could only find the ‘stretch to cursor position’. This works, but it’s not as neat as just being able to stretch to a set number of samples like you can in audio editor.

Any ideas on how I can accomplish this in a smoother way?
Also audio editor limited in time stretching seems really weird? Is it a limitation in the algorithm? For my intents and purposes I just want to do a simple stretching of the waveform to match 4096 samples.

Sorry, not possible

It’s possible, but indirectly, as follows. But more generally, for the work you describe, the audio editor is better suited.

Time stretching needs audio material, to derive stats and extrapolate new samples.
You can’t start too small.
Maybe, you could paste the 800 chunk multiple times, and stretch that, then remove what you don’t need.

Thanks a lot for the very quick and clear answers!
I’ll figure out a good workflow for this based on this I’m sure.