Ben B, are you saying you don't have the functionality to cool your wort after mashing in? If so, depending on your size, is it not possible to put together a moonshine-style copper coil cooler? Alternatively, you could reference the farmhouse brewers of Belgium by using a koelschip/coolship; it's a wide, but shallow vessel that your wort is sent to after mashing in - spread out thinly, it cools quicker. If you can get your wort down to yeast-friendly temperature in a couple of hours, you'll be safe.
ALTERNATIVELY, if you are questioning whether you need to rapid-chill/boil to prevent something like DMS, most distillers won't do this. One example is Scotch Whisky distillers using 100% malted barley. They mash in using three 'waters'. Out of a example 19,000 litre wort, first water will be something like 7000 litres at, say, 63.5c. After mashing for 15-30 mins, this wort is run off into the fermenter (cooled) and inoculated with yeast. Meanwhile, the second water goes back onto the grain: 12000 litres at e.g. 75c. Eventually, this is also run into fermenter (cooled) where the yeast has already started its Lag Phase on the first water (all enzymes are retained in the first water to convert starch to sugars). Finally, third water goes onto malt at e.g. 88c at 7000 litres. This then becomes the FIRST water for your next mash, having pulled the last bits of starch out of the current malt.
Sorry for the long-winded response, but I hope that helps.