Mash at 152F/67C for 90 minutes. Why not lower in temp? Because I’ve seen good experimental data out of a major yeast firm that shows 152F actually yields better attenuation (even as it produces a different sugar mixture that seems like it should attenuate less). The same research shows that a longer mash does boost attenuation, hence the long wait here.

Boil and chill as usual, then pitch your yeast. You might use a starter, despite the low gravity. We want to make sure we get a good start and finish on attenuation. Don’t misread this, though: we’re not shooting for an overpitch, we just want to be sure we avoid an underpitch, which can reduce total attenuation. “Enough yeast” and “even more yeast,” though, should yield about the same rate of attenuation, so one pack grown into a 1-1.5L starter should be fine.

Ferment a little warm, again, to bump up total attenuation. 68F/20C is warm for an Alt, but the 1007 doesn’t produce much of an ester profile and a larger-than-strictly-necessary pitch will keep the esters away, so you can get away with it. Leave it go for about two weeks at that temperature, and then cold-crash and lager for another two weeks. Package, carbonate to 2 volumes of CO2 (why are you thinking of going higher? We want it to seem lighter/thinner, remember?), and enjoy.