Ouch. How strong are the enemies and bosses?
Oh yeah, forgot to mention, but in some ways, FE12's Lunatic is probably one of the better examples of a hardest difficulty post-GBA era. Yeah, ambush spawns are bullshit and stat inflation is even worse than Maniac. But compared to RD them just taking away a few useful items toys Warp and the Silver Card aren't really losses. Sure, it makes the game a bit more tedious, but Rescue is a very powerful tool that is almost as good as Warp -- just requires a bit more preparation and knowledge about how the game works to abuse (learn about rescue priority and classes that can cross certain types of terrain). And regarding the Silver Card: you shouldn't be buying a lot of weapons as the game already gives you a steady supply of them through units who join, chests, and bosses. Just making good use of forging and effective weapons ends up saving much more money and weapon uses.
Personally, I only visited the shop once in the endgame and that trip turned out to be a waste since I just ended up buying a bunch of killer weapons that I had no need for thanks to the dragon-infested final chapters. It would be nice if the game you something that was at least half as useful as Warp and the Silver Card instead of giving you fucking Vulneraries, but not having those two items are far from being the only problems with Lunatic and Lunatic Reverse.