This is my current vehicle.
As far as I am aware of the kitchen unit is useless once you have the onboard chemistry lab. You should definitely get the welding rig as soon as possible (one thing you can do until then is to make a makeshift welder and install the battery storage mod so you can install vehicle batteries. Then you can get any car battery with a storage of 2500 installed on it. You can either find a battery that is full or after a bit of riding around with your vehicle and a truck alternator on the engine you will be able to charge up the car battery giving you a decent amount of power to weld with. )
I have 2 200 liter tanks installed using Shards Misc Mod (maybe there are other better mods out there, but I’ve only tried this one and I like it. : https://github.com/Lorith/Shardstuff-CDDA-Mod)
I built this baby from the ground up and I highly suggest you have two engines on it at the same time (hopefully with different fuels gas & diesel or electric) so you can take as much advantage from the fuels you find in cars. Also you should always have two engines because if your vehicle is stationary and next to a shrub, one engine might not be strong enough to push through and get you moving, this is a problem if you are surrounded by zombies and bleeding out/ in too much pain to fight back. I feel like no one uses rams on the side of their vehicle but I really like it for the rp value as well as for the extra defense I get from zombies because even with military plated rams and heavy duty quarter panels, they can and have broken through into the inside of my vehicle.
Also this is my mobile fully self sufficient base, 7 tiles wide, 14 long. I love it, and it has more than enough storage for everything I need (I have two cargo racks found in shards mod giving you 1000 liters of space to store things) My plan is to travel all around the ruins of the earth with it.