However, the thing that takes a lot of room is doing minor changes to the scripts, texts, map data etc. you edit afterwards because I believe that the tools, that support repointing, will always leave the original data in the rom you edited afterwards and even by expanding long datas with a byte or two, you can already double the size it uses in the rom file.
To do the job "better" would be by opening a hex editor and doing a copy --> paste of the data you wish to repoint so that you'd be repointing it manually instead (yet it's no way impossible to just put down the offsets that define the data you wish to repoint, repoint the data) and then could delete the original data (by changing it to FF's in this case). That way, you could save a lot of space but it's up to you whether to use this method or not.
*I do so myself but when hacking GB/C games, it's necessary to be done.