Welcome to the forum!
As I understand it, this is not a respawn question: the respawn works fine. The problem is that you want the respawn marker to be close to a vehicle which moves the whole time.
Assuming that's the case, you're laughing. Create a little script:-
; this script attaches the respawn marker to the wagon
#loop
"respawn_West" setMarkerPos getPos jeep1
~3
goto "loop"
Syntax not guaranteed, and that's not a working script, just a sketch. Depending on exactly what you want you can fancy it up a little. For example replace
getPos jeep1
with
[(getPos jeep1 select 0) + 3, (getPos jeep1 select 1 + 4), 0]
which will put the marker 5m roughly northeast of the jeep.