Yeah, what I wound up doing was pairing Chrom with Frederick and just had Frederick tank that pass. Which is super goddamn lame, but it worked. I also managed to clear Paralogue 1 and get the Rescue Staff which I used to get the mages out of there at the start.
My main complaint is that the enemy levels on the random skirmishes are way higher than my guys, I'm not sure if this is intentional or if my group is underleveled or what. Until Chapter 5 I was trying to use Frederick as little as possible (mostly as bait) so he was only level 2 so I don't think he was stealing a lot of XP from the group. But going into Chapter 5 Chrom/Tactician were both level 8, Lissa was level 7 and then everyone else was level 4 or 5. On the skirmishes though all of the enemies were level 7 or 8, which results in everyone that isn't Frederick (and sometimes Chrom/Tactician) getting one-shotted. So I don't know what the hell. Should I just be focusing on ~8 or so characters to level up and just not worrying about trying to level everyone up at this point?
As an aside I got Donnel from that Paralogue, should I actually be trying to level him up ASAP?
Edit: Yeah, after spending literally at least 8-10 hours trying to beat Chapters 4-6 on Hard with no deaths I'm just playing on Casual now and not giving a fuck. Literally not having fun with the game. Have cleared more FE and tactics games than I can name, I have no idea why I can't do this since everyone says Hard is totally fine, but I no longer care.