Will size of a basin impact stability of an object to float above the water?

Use the equation for lifting force. Fa=pgV. P=density, G = gravitational acceleration (ms^-2), V=dipped volume (m^3). Note: Fa (lifting force) is measured in Kg/m^3 and the G constant (gravitational acceleration)always = 9.81ms^-2. Find 10% of the weight of your canister and change the variables of the equation (density of water and dipped volume) until the the Fa (lifting force) matches 10% of the weight of your canister. Do all of this on paper not on the actual apparatus as it will take a very long time! When you have the maths correct change the density by increasing salt content of the water and dipped volume by adding water to your canister.To answer your question about the dimensions of the water, no it doesn't affect the bouncy. Obviously if you had a puddle of water your canister is not going to float but if we are talking about 4m^3 compared to 16m^3 of water there is no effect as far as I am aware.