You can kitbash a base and create something original on top, that is imo the most efficient workflow to get something that fits the game art style. It is also a very powerful training tool to understand how vanilla sprites work. The trick being that the underlying kitbash is only used as a reference for colors, noise, details, composition and overall to keep an eye on vanilla parts to match them. That huge sprite there? By the end of the process the only vanilla parts left were the bridge and the weapon mounts. Everything else was original stuff painted on top, but it closely matches vanilla. It's the same process I used with several other sprites:
|
|
|
Only the engines are visibly partially repainted vanilla sprites, but the whole spine section used to be kitbash. |
| This one is a bit closer from its kitbash source yet still 4/5th original. |
We are not talking about making sprites solely from parts picked here and there: there is no limit to the amount of paint-over you can do on top of a kitbash, so there is no reason to not make that first blockout from vanilla ships. Its also far easier to work from a canvas that isn't empty.
Your "outline, structure, lighting and colouring" are indeed unique, and they might not fit that well into the game because of that. If you want to closely match the original game that is, otherwise forget everything I said.