TKL + Numberpad is a good idea...
The numberpad will let you experiment with smaller layouts as well if you want..but IMO, the big space gain is going TKL...the rest feels less significant (even if the amount of space is the same).
I would consider what using the numberpad means..
For some people, they just prefer to put in numbers that way even though they're not doing heavy numbers work (big extensive spreadsheets for example). Eg. If you're doing it because you enter in some IP addresses, learning to use the normal number row, IMO, is more than fine (and just as fast given no hand swapping).
If you're really crunching out heavy number use...dedicated numberpad...easy decision..