I'm going away for the weekend next weekend and my aunt will be looking after my piggies.
At the moment, I write down what I give them for every meal, so I will be showing her that book in case she gets stuck, so she can use it as a reference.
But basically, I will make sure I have all the veg they need, wash it all and place it in one designated container. So she knows that's pig safe food.
Then I'm toying between two ideas: 1) writing up a detailed list of what to feed when, or 2) prepackaging meals - so measuring out and prepping each meal, putting it in a separate container and labeling with day and time.
I'll also write down how much pellets and times.
I use fleece bedding (not sure what you use?) so I'll do a full cage clean just before I go, then show her where the stuff is for their toilet area in case it gets really bad, but otherwise I'll change it out as soon as I return. We're only going for 2 nights, but since you're going for 4 nights it might be worth explaining to your boyfriend how to clean the bedding if you think it'll be necessary.
So basically:
1) do full cage clean right before you leave
2) show boyfriend where pellets are, and write down how much and what time (maybe even write this on the bag)
3) show him where the hay is and write down times to top it up
4) stock up and wash all veg and place in one designated spot. Write clear detailed lists of which veg, quantity, what time