Why not do a credit cap of 200,00CR (without modifications) and nothing under 850kg/1874 lbs with weight reduction? That way cars are a lot more even. you can change these numbers just a idea.
I'm also not keen on the credit limit, but the minimum weight is a 👍 from me.. Well, the elise is banned only on 1 reason i guess, it's lightweightness.. So, with a restriction on weight limit, maybe it will reduce the unfairness.
Also, why no put a pp restriction? Example, for T200, with a max of 200HP combine with a 400+pp limit, it should be adventurous. Just my 2 cent..