hogtie technique found in video

[Tinker D]

Well, as long as the rope from the chest coils to the knee coils or ankle coils is taunt, it really doesn't matter where the wrist coils are. So maybe a floating wrist coil with its own adjustment could solve this problem.

[SharkTied]

My preference is for secure feeling but easy to escape. The technique in this video appeals to me more than one using a cinch knot for that reason, but she has more freedom of movement than I'd prefer.

What's a good way to make this a little more strict while maintaining the ease of escape? At first thought I'd say shortening the rope connecting the ankle and wrist restraints would do it. Would just need to take care to not shorten it too much, I guess, or it could be hard to loosen the tension enough to undo it.

[Tinker D]

The tension is now on your waist in stead of pulling your wrists,

Yes, but it's not what the tight hogtie is about - bow-like tension. What you described works perfectly, you can experiment with harnesses (like what @Tinker D did), with rope routing, but the end result is: wrists are fixed to the waist, knees bound.

What I would like to achieve is: arched spine, straightened arms pulled towards the knees, bent (or not) knees. Legs can be "pre-bound" by looping ropes around ankles an thighs (knees fully bent).

The end result is very tight and very restricting position. Crawling and moving is VERY difficult. But the most serious problem is painfully squeezed wrists, because it's the weakest link in the whole construction.

ok, to arch the spine like you wanted, connecting your ankles to the wrists may not be the way to go. All the pictures I have seen shows female that have short torsos and long legs.

For guys, I think that a ring on the chest coils, with the shoulder ropes, would be the best.
Here is I would do this. I would first wrap about 4 to 6 wraps of rope around my arms and chest. Add a ring to the small of my back and keep it in place with a set of shoulder ropes.

Get my wrist coils ready and off to one side for now.

I would tie my ankles, knees and thighs. Thighs are always the hardest to tie and keep them in place. I would now add the SRD to the ring behind my back.

Now comes the threading. and tighting. In this case, you will not really need a chinch noose for the wrist ropes, but you can use one if you want. A Zip-tie would work.
Start with your hog tie rope at the SRD. The rope needs to be long enough because of the long distances it has to travel. Both ends are going to travel down your back to your ankle tie, through your legs and back toward the ring at the small of your back. Tie the rope to the ring, so that when you pull on the free end of the SRD rope, it will pull your ankles toward your back beyond your wrists.

Now, before you start pulling on the SRD rope, Get your wrist coils and while your legs are still straight, Make sure that your bound wrists are outside of the SRD ropes. So, when you pull on the SRD rope, Your ankles will be drawn toward the SRD, causing your spine to arch like you wanted. Sa the hog-tie rope pulls your ankles up. your arms and wrists will be pulled out and away from your body, straight and your ankles will jam on your wrist coils giving your desired Hog Tie with Arched spine.

[Like Ra]

This is how it's properly done:

youtube.com/watch?v=kJCbiz5ywKY

It can be adjusted to make it inescapable without a knife (the knee-wrist strap can be replaced with a disposable nylon cord).

[Tinker D]

Ok, but.....
Again, the arms are not away from the body.
Instead, I would do the same thing except, instead of of connecting the wrist strap to the knee strap, I would place my wrist strap outside of hog tie strap and use eather a zip tie or chinch rope to tighten the wrists.
In this way, your arms will be held away from your back.

Did one like this last nite. All went well till "CRAMP".

[Like Ra]

your ankles will jam on your wrist coils giving your desired Hog Tie with Arched spine.

I think it depends on the flexibility. For example, if you sit on you knees with ankles together, arms behind your back, you should be able to touch your ankles without arching too much. Now try to reach your knees.

Or do I misunderstand you?

Again, the arms are not away from the body.

How can they be away? Fingers can be away from the ratchet, if you place the ratchet as close to the knees as possible.

[Tinker D]

Ok, I now understand.
To get that arched spine, your wrists needs to connect to your knees, not to the ankles.
Got it.
No, I misunderstood you.