Our systems could not be more different but I here is something I have found that could actually be more valuable to you (at the scale you are brewing) than it is to me. I am getting higher gravity extract into the kettle by doing an alpha rest. No question about it. For example, I will get better extract into the kettle by mashing at 148F/40min. and then 158-162F/20min. (60min total) than I get by doing 148F/90min. I am not noticing any difference in fermentability. Now, there's really no reason for me to chase efficiency (at your scale it probably matters) but that's not what this has been about. I am getting very predictable extract with this mash schedule. When formulating a recipe or rebrewing an old one I simply look at Kai's chart of predicted first wort gravity with 100% conversion and every single time my gravity has been dead-on or, actually, one point higher than predicted by this chart.
I know that for years Jamil advocated long mashes when mashing low (your situation) or with a lot of flaked adjunct. If I understand things correctly, in most mashes the beta activity peeters out around 30min+/- so you would be relying on alpha amylase to do any remaining conversion (well under its optimum temp) for the last 60 min. I have conducted several mashes with 15-20% flaked wheat and/or oats with this 148/40 158-162F/20 schedule and they have all give me the same predictable results I noted above.
Hopefully there is something useful to you in this. I guess you would have to decide if the extra efficiency and extract predicability was worth the trouble of stepping the mash. But I think you that certainly you could get away with 60 minutes instead of 90 and that has to be worth something to you.
ETA: I should add that this predictability has panned for me consistently from a 1.034 berliner weiss to a 1.086 BVIP Which when no-sparging (BIAB in my case) represents a wide range of mash thicknesses.
Edited by neddles, 15 November 2015 - 09:09 AM.