I genuinely don't think there's a solution to this issue that doesn't involve shutting down either Open mode or Solo/Group mode. The game needs to make its mind up what it wants to be.
I've said this elsewhere, but if FDev ask how I feel about the issue I'll say it again. Sorry if I'm being repetitive. But I loved FE2 and FFE, and I waited patiently for a sequel to those games. This isn't it. Combat wasn't ever something I was particularly interested in, and it isn't in ED either. I don't say there should be none, but for me combat will always be a nuisance, and a distraction from the game I want to play.
That makes me a carebear, I'm told - but the thing is, that doesn't matter to me. Whatever you want to call it, I just don't find it fun to blow up or be blown up by other players. So I don't do the former and I try to avoid the latter.
You are into combat, though, and that's fine. But the thing is, I think what we really want, you and I, are different games.
I want a game that offers detailed character creation, realistic flight physics, a chance to carve out a story as a space truck driver. I want to deal with space truck driver problems, like finding jobs, keeping the ship in good repair, learning to navigate using proper orbital mechanics, dealing with agents, fixers and middlemen, avoiding legal and political troubles, and so on. I want combat to be the rare last resort I'd expect it to be if that were my life.
You want a game that maximises the excitement and playability of the combat model, and lets you measure your skill against other players. I get that, and fully respect it. It's just not my game.
I signed up for ED before Offlinegate, when I thought true, offline single-player would be possible. The truth is, as selfish as it may be, I just don't care about Open mode because I never wanted to play in it. On the other hand, I never wanted to impact it in any way either: I influence your galaxy because I have no choice, not because I want to undermine some Power or other, or contribute to a CG, without taking any risk. I don't care about Powers and I don't care about CGs. They aren't what Elite games were ever about.
So, FDev, if you want my solution to the problem, it's this: give me First Encounters II (Second Encounters?). Put ED's visuals and audio over the top of FFE's gameplay, and sell it to me, and I'll give you money to go play in my own private galaxy, and the Open players can get on and do their thing without me messing up their shared world.