I am pretty sure it that making "walk on vehicles" and whatnot were proven near impossible
Look at Ghost's Aircraft carrier
"GSF Aircraft Carrier (v1) - my last add-on
A vessel you can land planes on, walk on, drive vehicles on, and land helicopters on. This add-on has a custom air-raid siren that plays when you ram objects, has increased maximum damage of 1000, can be painted, can be used with the gravity gun, comes in two different versions, has a custom turret fire sound, and has an altered debris model.
You might have problems spawning the carrier due to it's size; try spawning them in large open areas underwater, usually in slate maps with water datablocks, in GSF Vice City, or in GSF Paradise. Or, try spawning carriers on elevated spawns and then use the gravity gun to bring them to water. Credit to Kalphiter for his no-mount script, which allows you to explore the interior of the carrier's wheelhouse and walk on the flight deck without mounting by typing "/nomount".
GSF Carrier w/ interior
Features an interior and ramps you can walk on, thanks to using a complex collision box and Kalphiter's no-mount script. This version also features 16 mount points, 5 of which are located in the wheelhouse. The ramp collision will not work correctly if the carrier is at an angle. The driver and passengers in the wheelhouse can be shot due how the collision box is set up."
