Temperature for fermenting a hybrid (california common)

I have brewed Steam lager twice at 20-22°C(68-71°F) using SafLager W-34/70 which has an ideal temp range of 12–15°C (53.6-59°F). We hit FG in 4 days, and bottled 3 days later. Both times at these temps the lager was delicious, and a few brewer friends were shocked when I told them what temp it was brewed at. Steam lager can be excellent.

At the higher temps it threw off a lot of sulphury aroma during fermentation, but once it had finished an sat for a couple of days it tasted fantastic so into bottles it went.

We have also brewed the same beer starting at 20C and dropping to 8C to lager for 4 weeks. And, yes the beer was different, but both were very drinkable.

Fermenting just a few degrees above a yeast strains optimum temp will not generate detrimental effects, but you could lose out on the bread and butter a particular yeast strain provides. 2112 from Wyeast can stop providing lager characteristics once the fermentation temp has surpassed 65F. With a 70F ambient temp, and keeping in mind that when fermenting your beer's temp will increase 1-2F, that puts you at 71-72F. I would say you are defeating the purpose of using 2112 at that point.

I would highly encourage you not to ferment outside. Unless you got a cooler large enough to fit your fermenter, in WI you would be talking temp variations of 20-30F throughout the day. This is not good.

If you are going to get a different yeast, I would suggest making a 'different' beer.

Alternatively, I would explore ways to control your fermentation temp indoors. One way to do this is to use a wash tub (or a 'keg' bucket), place your fermenter inside, and fill the rest of it up with ~60F water. The water will not only keep your fermenter cool, but act as a heat sink so your fermentation temp will be very slow to fluctuate in the 70F environment.