I have a hard time getting liquid treatments into my hair, too. It's the density/low porosity issue. I kneel on the floor, put my head into the bowl (so fact-first, upside-down) and pour things in, use the bowl to dunk, smoosh, etc. It takes a while... but it's a great quadriceps workout!
I think gelatin would clog a spray bottle.
Hang on to the conditioner. A lot of people on here like a heavier conditioner after a protein treatment. Or you may hit a dry period in the weather and find it works.
I sort of blog
I'm mostly away doing field work through mid-May.
Hair: curlybob, fine, dense, low-po, big waves/ringlets (2C/3A)
Co-Wash: Nature's Gate Herbal Conditioner
RO: YTC Carrot, Aubrey Organics GPB
LI: BS Shea Soft Styling Cream (HG)
Styling: KCCC, Garnier P&C Gel
1xWeek: low-poo, gelatin PT or Joico K-Pak
Hair Likes: aloe, coconut oil, humidity, protein, long walks on the beach