Using low oven temperature to accelerate proofing
Let me suggest a totally different approach:

Why not work with the cool conditions instead of against? 


You could let the dough proof for a long time, e.g. overnight in the fridge. This allows for a lot less yeast and hence a less yeasty taste, which is usually desired. Also, more complex flavors develop during long proofing times. (There is a reason french baguette may wait for two days before baking.) For a start, aim for about 5% yeast1 and use cool instead of lukewarm liquid. 
You might have to adjust your attitude, because this requires some planning ahead, but gives you more degrees of freedom on the other hand: Fresh bread / cake in the morning without having to get up before dawn and more tolerance with regard to proofing / timing - the dough can handle an extra hour or two in the fridge easily. (Especially nice if you have a baby or a crazy schedule...)
You could also dump the dough in cold water and proof it there. As crazy as it sounds, it works. See more here.


If you'd rather stick with warm conditions, I'd aim for 30°C for optimum (=quickest) activity. Yeast starts to die at about 45°C, completely dead at 55°C. Also, warmer dough tends to proof unevenly and have a "flat" taste (can't find a better word).



1 fresh yeast, percentage based on flour weight.

Adjust dry yeast accordingly: fresh to dry conversion rate is 1:3, so use 2% dry yeast.