your 750 is still going to need an oil tank, so unless you get creative I don't think that area under the seat will ever be totally open. Cycle exchange sells oil tanks that also hide your battery (pricey at $270) and that will clean up a lot (espically since they are low profile oval shaped. Considering you will pay about the same amount for a cr750 replica tank and your frame will not be totally clear anyway this doesn't seem like a bad option.