change it's parameters (for example, remove the difficulty retarget from the testnet completely... Set the difficulty very low and keep it there). Also, I'd be in favour of setting a fixed coinbase reward without deflation: Always 12,5 tBTC/block.
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I know there are other downsides to, like the fact that if these changes would be implemented, the testnet would no longer behave the same as the main net...
I don't expect this to be changed, I always assumed testnet was supposed to act the same as main Bitcoin. If it's different, you may still get unexpected results after testing on testnet.