The one gallon jugs I use have a mouth far larger then any cranberry I have seen. I added whole blueberries to my 6 gallon glass carboy with no concern, though they were a pain to get back out because that carboy has a smaller mouth then my 1 gals. I would go ahead and use whole cranberries, but perhaps look into using a bucket for primary fermentation so you don't have too many losses due to racking off the berries and lees.
Also, you have a lot of sugars going on in that brew. I won't say it is a bad thing, I have done similar. But you have honey, fruit, concentrate and you're planning on adding sugar? You could stick to just 2 or 3 of those perhaps.