If the kickspace heater is on the return pipe coming off of the 3' of fin tube (in the same bathroom) - I can't see how the kickspace heater could contribute anything more than the residual heat not expressed by the fin tube which would not be considerable. A circulator on the 3/4" loop feeding these two elements might push more heat through them but only when the boiler is fired up. Jumping the circulator pump you're contemplating adding off of the primary circulator makes sense. It seems you're trying to create a second zone for this loop and the two elements on it. To do that, there may be other factors to consider and a more effective way to accomplish what you're after. That said, for all I know (I am not a pro and have never added a circulator or a pump to any heating system), what you're proposing may accomplish what you're after; to increase the heating factor in this bathroom during the "shoulder" months. I like that you used "scoop" tees. Can you tell me more about them and why you chose to use them?