These poses are unfortunately can not always touch ground if used on beach. This is due to how Rockstar made the beach to create a sand sinking effect.

This effect has different sinking levels at every location, so it is impossible to create a pose that can stay right on the sand in everywhere.

Here is an example;
https://streamable.com/com42d

I'm truly sorry about this but as you can see this is out of my hands...

What you need to do is, freeze your character using Menyoo and have it's Z position adjusted according to correct your level.

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lying@on_beach pose made spesifically for 1 location. This is the photo that was requested by one of my Discord member; https://cdn.discordapp.com/attachments/989976481646145586/989983054128898068/sitting.jpg

The pose is intended to work on angular surface. If you want to use this pose in another place, you can do so by adjusting the character's Pitch rotation. However if you use it at flat surface the head's direction will be off obviously.

Here is the location and rotation for this pose made;

        <PositionRotation>
            <X>-3010.38867</X>
            <Y>10.6181049</Y>
            <Z>6.74963379</Z>
            <Pitch>0</Pitch>
            <Roll>-0</Roll>
            <Yaw>161.924591</Yaw>
        </PositionRotation>