Thanks for sharing your creation.
A similar method I've used which avoids any special sewing it to use exactly the method cavers and aid climbers use: Attach one ascender between a sit harness and simple chest harness and another on the halyard
above. To the higher ascender attach a climbing ettrier. If you have just a little weight on the halyard
, it will automatically feed through ascender attached to your sit harness and chest harness so bascially all you need to do is stand up and sit down to ascend. To come down you can either desceend or swtch to rappell.
If you wish to keep cost and weight to a minimum, you can fashion a chest harness and sit harness out of webbing, as well as tie a sling to length instead of buying
an etrier. In addition one can substitute prussik slings for ascenders, but the ascenders are much easier and quicker.
I prefer a large handhold ascender even at my waste as it makes it easier to clip and unclip the carabiner if swtiching to rappell.