A simple mode that adds a flycam (that allows you to teleport the player) and quicksaves.
F1 to toggle the fly cam
Scroll to adjust speed
Shift for speed boost
Ctrl for super speed boost
Hold Alt while scrolling to adjust fly cam FOV
Left click to teleport your player to where you're looking
F9 to save position
F10 to load position
Give it plenty of time to load in the chunks of the area you're loading back in for the quicksave, it can take a while. When trying to teleport your player it may also take a bit for the terrain to load in. Just keep clicking until it works.