I think you should carry ramp to lift the center of the flat wheel back up to normal height. Jack up from there to get the wheel off block, then off hub. First, much less overall lift with jack, so less likely to fall off. And just holding is not as likely to fall as while jacking. And given a fall, if it happens with the wheel off it is more likely to hurt you or vehicle. If you start up from normal height you don't get flat off, then need to "Up just a little more" to get replacement back on.