DUSSELDORF ALTBIER IN THE SUMMER

We have a tasting party in October, so I need to replenish my beer stock because it is severely diminished due to an unexpected rash of infected beers from an outside contaminate. I have a American Blond in the bottle and I need at least 6 or 7 more. My bright idea was to take a 'beer trip' with representation from the US, UK, France, Belgian, Germany and maybe one more.
I decided on making a Dusseldorf Altbier first then proceed to a Kolsch because that beer needs healthy, once used yeast to make it better. Also, these German ales are hybrids and they need a low fermentation temperature down to about 62F. The problem with this scenario is that it is the end of June and it is pretty freaking hot out there and me without a dedicated fermentation chamber. Well, I have a laundry sink and ice, so I will have to make the best out of this difficult situation.

Dusseldorf Altbier
3.9kg Pilsner
.500kg Munich 10L
.500kg Vienna
.110 Black Patent (last 30 mins of mash)

16G Magnum @60 min
19G Hallertau @20 min
20G Hallertau @1 min

1/2 tsp Calcium Chloride in Mash
2 ml of Lactic Acid in sparge water

Presently, the primary is sitting in my laundry sink full of water at about 57f. I need to maintain that temp for about 5 days then I can slowly warm it up. I have not yet decided whether to rack to secondary then commandeer the family fridge to lager it or just bottle then lager (after it has carbonated)
UPDATE: I bottled the beer last night and unfortunately, there was a distinct banana aroma. Sure, it may subside over time, but it is an indicator that the fermentation temperature was too high. I really need a freezer chest with temp control but no money for such extravagance. Sigh.