Most laundry companies don't make tablets anymore. I was bummed! They were terribly convenient.
Where is the "Travel size" section in
Walmart? I've never seen a mini bottle/package of detergent besides Sun or Purex at Dollar Tree or Family Dollar. Sun detergent works pretty well. I've been using the liquid versions for ages.
I have to use unscented detergent on my own clothes, so in the past I've washed out a small drink bottle (like what you'd buy juice in from a vending machine) and put the liquid detergent in for traveling. I measured in the detergent by the capful, marking the sides of the bottle with a permanent marker to show each load's worth. I'd just pour in the correct amount according to the lines. A 12 oz. bottle holds 4-6 loads of detergent, more if you use the concentrated kind. If you put the lid on tight and then put it in a ziploc bag, it should be fine. I'd rather not purchase detergent specially once I get to my destination, so this has worked well for me.