All those instruments are based on the VIX so it should be technically possible to replicate your own VXX or UVXY with some combination of VIX options. Therefore, there may be some other combination of options that better suit your strategy. But if the ETFs work for you, that's great. Keep using them. I've also wondered if one could be profitable shorting both UCO and SCO to capture the decay, but I suspect that the borrowing costs make that strategy unprofitable otherwise everyone would be doing it.