It soulds like you are going to be a maximum capacity with your mash in that cooler, so trying to do a mash out may be beyond your means. If you batch, I would say drain your cooler completely and sparge a little warmer. If you drain some and do an infusion to bring it to mash out temperatures, you will have to adjust your volume slightly because you are decreasing your thermal mass before your infusion. But hey, RDWHAHB whatever you decide to do I am sure it will work out somehow
