@Violet I saw the pictures of the device you referred to, Both designs are putting a lot of material between you and your lover. I have an idea (never tried it though):
The elastic doesn’t have to be below you. It can be above. What you will need is called an extraction harness.They are used by mountain climbers, rescue workers, military,etc. Cost new is about $200–300, but since you don’t need the safety certifcation you should be able to buy one surplus for a small fraction of this. This harness places two D-rings at your shoulders.
Using a simple framework made from steel tubing, attach yourself by the shoulder rings using bungee cords. You can adjust the degree of support and elasticity by varying the number and size of the cords used. It’s like being in a parachute harness.
Setting up and getting into such a device is going to be a bit more involved than the devices in your illustrations, but this has the advantage of there being no material between you and your lover. You can also adjust the “springiness” as I explained. The illustrated devices have a fixed degree of elasticity, based on your body weight.
The framework for such a device could also double as bondage equipment, with its overhead attachment points. Basically two vertical supports of suitable strength and a bar with two attachment points above.