I have read this post with interest, and would like to make a few comments and suggestions if I may. I respect Tim's position and the forum rules, so will make no mention of my new red mite product.
There are a few issues that are being overlooked here. Firstly, there is no reason whatsoever to burn any hut due to red mite anymore and incur the costs of a new hut - this didn't work for me in any event - I burned the hut, nestboxes, perches, bedding - all contents of the hen hut went up in flames!, I and more importantly my birds received around two weeks relief from the dreaded red mite before they followed the birds to their new hut. Futile, expensive waste of time!
Relating to the holiday re-infestation. Jet-washing or hose-piping a hut is the single biggest mistake any hen keeper can make. The water pressure may kill a few, but the vast majority will survive in the surrounding area. All they simply do is dry themselves off and move back in. It is also highly likely that mite eggs are not removed in this process, so they hatch.
Red mite that are not feeding on blood cannot breed, therefore they do not lay eggs, so this issue can be eliminated mostly.
Red Mite are migrating crawling ecto-parasites, they cannot fly or jump. It is highly likely that some mites were returned to the hut from the boarding facility. It is completely true that red mite do not live on the bird, they only feed from the bird at night as they try to sleep. However, to migrate they must hitch-hike a ride on something, or someone. This does not necessarily mean the hens were responsible - the possibility exists for mites to hitch a ride on humans (clothing or footwear), birds, animal crates etc. You only need to carry one mite back to any hut to begin a new re-infestation. With a breeding lifecycle of 7 days, its not a long process. Red mite will also hitch a ride and attack mice, rats, wild birds etc who will carry them to their new home as they visit various gardens in search of food.
I would suggest that before using any such boarding facility, a conversation should be had regarding their red mite eradication procedures, and be very wary if creosote or lime has been used - not only are these illegal to use in egg laying hen facilities, they are dangerous to bird health and egg contamination. Creosote is carcinogenic (cancer causing), amongst many other life threatening possibilities) and lime is caustic (burns). You should inspect the premises thoroughly prior to agreeing any boarding, to satisfy yourself an infestation of red mite does not exist. I also suggest that you check your clothing before getting back into your car, and certainly change clothing and launder on a very hot wash, then take a long shower once you return home, before going anywhere near your hen huts. Check your car also for stray mites.
When visiting breeder facilities and poultry auctions, undertake the same checks. ALL new birds should be quarantined on every occasion, not only to guard against red mite but to prevent other diseases from being introduced to your flock. Once you are happy, after a week at least, then and only then should introduction occur.
Until red mite are eradicated from every hen hut, smallholding and farm their numbers will continue to proliferate, and inadvertently human behaviour assists their travel between premises to carry out their deadly habits.