You are misunderstanding what this solves. Believe me, if some easy solution would have existed, it would be there already.
So, what does it solve?
Essentially a fork before such checkpoints would destroy the network. Although the probability is low, this is a very non-trivial effect. Checkpoints eliminate the possibility.
If somebody has huge computing power - it can ruin bitcoin in many ways. Checkpoints eliminate only one of ways, but it still can be destroy in many other ways with such computation power.
Let say, there 32 ways to destroy Bitcoin using high computing power, checkpoints eliminates only 1 of 32. But there still 31 other ways to use this power - so, really checkpoints do not bring anything except compromised credibility of decentralization.