Well, I figured it out! It was a mod order conflict, another mod "replaced" the respawn options and was higher in the list, when I thought they'd just be *added* to the list. My bad!
On another matter... I just wanted to point out that, in the hotbar of the cockpit of this rover, the first item is a cockpit control, and... It toggles "show on HUD" on and off! I *somehow* suspect either that was not your intention... Or else you're a bit of a troll! ; p
Anyway! This is indeed exactly the kind of thing I was looking for, and has worked out nicely for the 30 minutes or so I have been playing with it! Thank you!

Exactly the kind of thing I was looking for! Unfortunately, it doesn't seem to appear in the in-game respawn option list?

works but it always makes me spawn on mountains. Unable to respawn to any other different location. Wouldn't be so bad, if the vehicle could traverse the really rocky terrain it lands me in,

it wont show in mod list

Hey Nice to meet you I am Starprime, there was not a comment section on your account so this is the best to invite you, I am co hosting a 2020 Builders award thing like the Emmy's but for the space engineer workshop, it will be on discord. if you would like to learn more about this I am available at any time