In theory yes, you can use whatever amount of liquid as long as you do your math correctly.
Your goal is to have a solution which contains the correct amount of SN (mg/ml) to be detected by the test strips with as minimum error as possible.
But mixing the SN in the bottles and using them to perform the test seems unpractical to me:
- you can't use a spoon to stir the solution
- you have to shake the bottle until the SN has dissolved and that may not be easy to tell
I suggest you use graduated beakers.
Additionally, somebody suggested creating a solution which matches the middle range of the testing strips because that range is the most accurate according to them.
See
https://sanctioned-suicide.net/threads/testing-my-sn-using-the-aquarium-testing-strips.31522/ (very straightforward) and
https://sanctioned-suicide.net/threads/sn-aquarium-purity-testing.34630/ (more math involved but worth a read)