I can't afford Home Plate in Diamond City, so Red Rocket Truck Stop seems like the next best thing. Is it possible for Red Rocket to get attacked by raiders? I have another character that put tons of stuff in the workbench in Red Rocket and it was always there (but then again I have 4 turrets guarding it). I have no settlers there, nothing of any interest except for the workbench loot and T-45 power armor, will it be safe?
Yes, it is possible for any of your settlements to be attacked by raiders (or super mutants, rust devils, etc). From personal experience, neither Red Rocket nor Sanctuary have ever notified me that they were being attacked and that I needed to defend them, but Red Rocket has been attacked at least once every three times I stop by there.
Here is a thread where people are talking about their Red Rocket being attacked.
Had three raiders try to ambush me around the time my first Red Rocket settler was assigned to the gardens.... I offed them pretty quick though.
My settlement or base is the red rocket station and I get attacked regurarly, almost always by super mutants and some times raiders. Have like +80 defense orso.
I haven't had a time where it notified me that my Red Rocket settlement was being attacked and that I needed to defend it, though. Not sure if it's because I send every single companion to Red Rocket or not.
Your Red Rocket Truck Stop won't be raided.
The key is the lack of settlers. Any settlement without settlers will never be attacked. You don't need any defenses there except to help you when you visit it.
On survival, I deliberately make some settlements empty to achieve this because I cannot fast travel, don't want to run back out here after setting up a Provisioner, and just don't feel like building an area up. It sometimes involve killing existing settlers, but that's life.
"Raided" as in attacked by raiders? Yes! Any of your settlements can be attacked.
If you mean "raided" as in looted by the enemy then Yes/No. For you to fail to defend your settlement, you would have to have a very very poor defense.
But nonetheless, if you happen to fail, the ramifications aren't all that harsh really. You would of course lose all the dead settlers, some or all food crops and water in the workbench, and you would need to rapair stuff like turrent and the such. Your loot would remain as is, though.
To prevent defeat, set up some turrets on top of the building to boost your defense. This number must be higher than your food + water. Meeting that requirement will keep prevent raids from happening as far as I have observed.
Coincidentally, I tend to send all my companions to Red Rocket, since its a small, easy-to-fortify location and it makes it easy to find my followers, while keeping them out of sight in my main settlement. I tend to pimp my followers with my secondhand (still really good) weapons and armor, remember to give them ammo, though. That gives me some peace of mind for additional protection in case any invaders were to get past the turrets. But, that's me being paranoid. Them getting past the turrets with the appropriate defenses has never happened.
An extra tip: Don't leave fusion cores in your unused power armor frames. Settlers and companions will hijack them when your settlements get attacked. Most times you can tell them to get out, but remeber that Bethesda has a lot of bug and there as several reported cases of this being a big issue.