My first AG set up was 2 5gal. Rubbermaid Coolers. After a while I thought, why not go bigger? So I went to a sporting good store and bought a 10 gal Igloo cooler for $50 and put my mash fittings on it.
The Igloo held the temp better and I was happy.
All of a sudden I started getting stuck...
I just started all grain in January.
I would like to add 2 more bits of advice.
1. Make a wet run with your new equipment.
Go through the pre-boil process using hot water.
Monitor your temps and times. If you run into a problem you haven't wasted grain. This also helps to get the "new"...
I have the same temperature control problem.
I have used Saflager yeast twice at room temp (cool)
and it worked fine.
One sugggestion: I would recommend going to all-grain.
If you do you will never go back to using extracts.