If you're ultimate goal is a twin, just get the twin to start with. I had only 200hrs when I moved to my twin. Because buying and selling a plane within a few years is always a rotten deal. Not the depreciation so much, but all the stuff you fix it for. Because we are humans, we can't help ourselves. It's like doing your house up - it always ends up twice as expensive in the end because you went for the fancy cabinets and carpets and Farrow & Ball paint…
Buy your last plane first. Get the twin to start with and put your money into that.