First
My father lots of tomato plants and use the method of “fertilising” them and watering in to some degree at the same time.
This consisted of putting a small or large depending on the size of the bush can into the ground besides the plant, emptied of soil. The can have the top and the bottom cut off so it’s only the tube. He would then collect pig manure preferably or other make a slurry of it.
He would then fill each cans when ever low but once week would be typical.
If you are worried about watering and not bushcraft methods but want to have tomatoes when you come back from a meet well Lidil’s this week has a watering timer £12 for timer for irrigation. Job done