I hate to bust the plan, but that won't happen. Mainly because of one thing, you are throwing paying customers into the deep end. It is basically saying, don't pay for full membership, wait and wait 6 months to build up a solid country (if you can), then you can declare war. Would the GM actually encourage that? Hell to the No.
If you pay at the start, and wait 6 months to build up, you'll already be at WL3, and under siege. I waited a good few months before I declared war, building a strong econ, then buying weapons, then learning the war game.
End of the day, either WL needs to be ditched, or there is no longer cheap war protection for a full on war game. Would either happen? Looking at the polls, I doubt it. The polls say that there are more econ players, rather than war players. Look at the amount of people looking for cheap war protection. Look at the current poll on war levels (more no's then yes'). As vocal as those who like war (me included sometimes), there are simply more people who want to play peaceful, rather than aggressive.
As much as I might want to reduce some powerful econ players into rubble, it doesn't look like it is going to happen anytime soon. Simple math is, there are more econ PAYING players than war PAYING players, and for a website such as this, it'll have to go where the money goes.
I like Maestro's idea, but I'll put forth my one.
WL1 - Everyone starts here. No different to what is now. 3 C3 Wars push you to WL2
WL2 - Allows for 1-3 C3 Wars. Allows you to build up a total of 6 countries safely (1 main + 3 WL1 Slaves + 2 WL2 Slaves). 3 C3 Wars push you to WL3.
WL3 - Free for all. You can be attacked, attack others, only your main is in SM. You can now join federations. Only half of your slaves can have WP on max, or all for a set holiday period. Win a successful PVP war or 3 C3 wars to enter WL4.
WL4 - Last level. Can attack all WL4 players, and inactive PVP countries (haven't logged in 30 days).