I see only one proper solution.
Agreed warp like paradox games has.
Player A wants to warp forward in time, and presses the time warp button. Player B finishes whatever he's doing and also presses the time warp button. And we have time warp x2.
Any player should be able to cancel time warp at any given time. And any player could do all functions at base like research, upgrades, shipdesign and so on regardless of what time warp is Active.
The instances thing does create all sorts of time paradoxes.. and that means No reverting also..
Also an option for Coop mode and competitive mode would be fun. Where in Coop mode, you could share research, reputation, kerbals, ships and base buildings, ect. But in competitive mode you would have different of base location and not shared reseach, rep, kerbals, ships, ect. You could infact sabotage your friendly neighbours launchpad.. anyone see a cold war becomming hot? Space race? Star wars?!!
Make this a 20usd DLC and i would buy a 10 pack for my friends!