I do not see the big fuss about xps. You go up to level 15 so fast that it become boring point of view progression after that... especially if you are rich by then (no real point playing after that). Levels serve no purpose in this game since you do not gain hps like in other games. In fact, you should not have levels, just xps to spend on unlocks. I would add more unlocks (I do not see them as skills, more like computer upgrades). I would work with an xp or points system that you invest in upgrades, the more upgrades you have, the more expensive it is. Also, it would allow you to unlock everything over time, alot of time. Need more unlocks like trading, diplomatic, political, colonization, and many others... too many skills focused on combat. Sure, if this was a shoot'em up game, it would make sense, but it ain't.
Still think ships that cannot be salvaged should not exist in the game, their resources being added to the debris field instead. It saves pc resources for something more significant and useful in the game, also no need to worry about those for the dev anymore if he removes them. If you cannot salvage them, just remove them. I never use a SP to salvage anything smaller than a battleship-sized ship anyways... you do not gain enough SPs to waste on ships you can buy for a few bucks (at that point, you are super rich and can buy anything). The game would still generate the same amount of ships, but you would be able to salvage them without a SP and some only salvageable with the salvage unlock or a SP.