I also use a dual-system. I have an extra-short Thermarest pro-lite for my shoulders to hips, then two squares of blue foam- one for knees to feet and the other (actually a rectangle) to add width under the Prolite. I find that I need the extra width for warmth, but the Prolite, although small, is sufficient for cushion. The useful thing about this system is that the blue foam doubles for a sit-pad. I NEVER sit on my Prolite outside of the tent.

I do the same "blowup then deflate" for comfort. Only other thing to consider is that blow up pads can deflate a bit as the night gets colder because cold air has less volume than hot air. This is why you should not leave a fully blown-up pad in the tent during the day- it gets hot in a tent and the extra pressure may damage the valve.