It would indeed be helpful to tell people where you are based, also a bit more about Monty - age, is he neutered, what you feed etc.[some people may not be happy with feeding raw etc] . Is he ok with cats, small furries, children etc.
Whether you are able to cover any remuneration or "just" food, vets bills, treats etc.
Other things you need to think about is what happens if Monty does unfortunately need vet treatment [or sadly worse - do you trust someone to make that decision if they can't get hold of you?]
Is Monty on any medication? Need to think about repeat prescriptions, is his sitter ok to give meds etc.
Exercise - most people do not feel safe letting someone else's dog off lead so maybe a harness and extending lead [do not use an extending lead on just a collar, too easy to cause permanent neck damage]
What about if Monty damages or destroys anything in their house?
You might be lucky and find someone on the board ready to take Monty for you - obviously you need to meet up and make sure you are all happy with the arrangement, and that the dogs are all happy too - maybe start with having Monty over night, then for a few days just to make sure he would settle there - it also builds up in his mind that you left him for a short while but came back again.
Most dogs are not as loyal as we like to think, and as long as they are getting food, walks, cuddles etc they are quite happy
There are pet sitting arrangements available where Monty would stop in his own home nad someone would come and live there for a bit - but they are not cheap and for an extended period may not be viable.
Younger dogs do adapt well to kennels, again do the overnight thing etc, make sure the kennel is recommended, visit and see that it is clean and that the dogs are happy - regularly exercised etc.
It is always a concern when leaving your dog with someone about how careful they are with doors gates etc - Cavaliers can be very fast if someone is not used to them, they have an incredibly inquisitive nature and of course no sense of danger at all, we have seen too many lost in tragic accidents just on the board.
Lots to think about but please post more information and maybe someone will be able to help.
When you do come to leaving Monty, please make sure that he has a familiar blanket or bed and some favourite toys, his own food for at least 7-10 days if they need to swop him on to something else, medication if necessary, instructions regarding his routine [meal times, walk times - length, frequency etc, bed time, treats]