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""I don't understand why you think the definition belongs only with momentum/time.""  the reason is pedagogical within the physics discipline.  it would be a tautology to define the Joule as the amount of energy required to move a body against a force of 1 Newton the distance of 1 meter, then at the same time, define the Newton as 1 Joule per meter.  it's true but it says nothing about the quantities of the Joule or of the Newton (nor anything about their dimesion).  it is not like the chicken and egg, we know which one comes first (meter, kg, second come first, then the Newton before the Joule). the Planck force is a derived unit and will have to be the Planck unit of momentum divided by the Planck unit of time.  the fact that it comes out to be the basic tension in string theory or in, general relativity, the force that is the conversion factor between spacetime curvature and the energy density giving rise to it or, if multiplied by the fourth power of the (dimensionless) circular orbit speed some distance from a central body that it tells what the body would weigh at that distance, all these are fine and good, but they are the result of working out hypothesized physics problems, they are not the definition.  what if you worked out some other basic physics problem (say the basic tension of a string) and it came out to be 2 FP? or 4 π FP?  would you say that the force solutions to such are the definition of the Planck force?  it doesn't matter what the system of units are, once you have those 5 base units defined, there is no freedom left to define the others.  their definitions are purely consequential.
 i think you need to word things according to the most common terminology.  i fixed it a little more.  i inserted edit notes (invisible) that ask what does it mean to ""distribute energy over a gravitational radius""? and what does it mean to ""distribute energy over the Compton wavelength""?  unless you expect your encylopediac readers to know, even vaguely, when or where or how or why such distribution of energy is being done (thus defining the rate of such distribution), why say these words?  also, there still is no citation other than Schwartzchild radius, which i did.  so a reader does not think that this was all just made up, you might want to include references to other stuff.
 i fixed the convention errors and format errors (some just now).  do a diff comparison to see what i did.  "