@Celticrose67 You could try locking the other trailers doors for Everyone while empty. But it doesn't always work though on a home lot, in particular I've found if you travel and return they may be in the locked area and you'd have to unlock it to let them out. I've also found them wandering in to wash dishes and ignoring the locked doors.
But now I see it mentioned the roommate idea may be just what you're looking for if you do have DU, I've only used it playing as a dorm roommate and didn't like that my Sims couldn't sleep while the roommates were moving around and they wouldn't stop cooking. But that may be worth a look to see if it works better now. I kind of gave up on it after one try, I should really try it out again as it's been a couple of years.
I'd also advise adding the fire prevention system and not just smoke alarms too. Lately I've found if Sims not under my control are cooking/using BBQs they may cause a fire. (Just had a whole load of houseguests cause chaos). So if you add sprinklers that should help, as well as saving your game regularly.
I forgot to mention too, to add extra income you could always add a few plants with harvestables. Maybe like a little allotment. Harvesting them to sell each day would earn more money, as would fishing if you're near water. I quite like the idea of a little trailer park with a vegetable garden/flower patch. I vaguely remember I had one in one of the Sims 3 games now I think back, with a big lake.
I meant to ask, i've seen the smoke alarms but where are the sprinklers? I've only seen the sprinklers for the garden.
@Celticrose67 The fire prevention system utility panel is in the same place as the smoke alarms, it needs a bit of space around it to fit it on a wall. If you go to the kitchen section of the build catalogue and choose the smoke alarm icon it will take you to them. Their category in the build catalogue is in the Electronics section.
I find them essential if I'm having Sims on the lot that I'm not controlling. There's a bit of random cooking and BBQing goes on in my game. (To the point I want to chase them away from appliances waving a Spatula at them!)
I'm attaching an image of it.
