Yes, some of us need conditioner. End of story.
Last year, I went to my hairdresser and simply asked for a sample shampoo & conditioner. They come in squeeze tube/sachets, and for my hair (medium length, medium amount of it, somewhat curly), there was enough for two washes from one sachet of each.
This year, I will try the same trick if I have time (I leave in four days), and if not, I'm going to decant my usual product into a snack size ziplock bag. At least this is resealable, and weighs virtually nothing. I also carry the world's smallest bottle (seriously - it's about one inch/2cm tall - I got it from a hotel years ago) with a tiny bit of Moroccan Oil in it. I carry a plastic comb instead of my usual brush, to save weight, and I wash once every 5-7 days (it's all going under a cap anyway..). I found this worked well for me!