Interesting plane, nice to se something out of the ordinary!

Yes, deltas do need a higher AoA to take off. Float's designed for "ordinary" aircraft will not work well then, either you drag the rear of the floats or you need a much higher speed to take of.

To remedy this i sugest you increase the uppward angle on the flaoats aft of the step to make it possible to rotate more. A ordinary plane need to rotate 8 to 10 degrees on takeof, a delta might need to rotate 15 to 20 degrees. An unwanted by product of this is that the plane will ride nose high when taxing, as flotation is lostaft of CGas the float is cut away to allow rotation.

A taildragger type tri float set up, two front and one rear, might be a good idea as this can be arranged to allow enough rotation. Or go for two front floats and one on each wing tip for more stable platform