Oh no! I hope you don't also come close to exceeding the recommended maximum daily allowance of alcohol at dinner, too! ;-)
Seriously though, please don't do this. Aside from the fact that I'm skeptical that soaking halloumi for any reasonable amount of time will reduce the salt content significantly, that salt is one of the primary things that makes halloumi taste good. When you've got an ingredient with a lot of dairy protein and/or fat, it prevents your tongue from perceiving salt. If you remove the salt, it will taste flat and bland.
As a healthy person who appreciates well-seasoned food— including the occasional meal that might not be consumed solely with my health in mind— I am incredibly disappointed when I have to eat a meal with someone who's completely paranoid about salt, fat, or any of the other things that combine with good technique to transform boring ingredients into delicious meals that are worth savoring. Unless your guests have informed you of a specific medical dietary restriction, or you have one yourself, forcing your dinner guests to comply with your prejudice against salty things doesn't get you a lot of style points as a host.
A single serving of halloumi is 50 grams. It includes a sight less than half the recommended maximum daily sodium level by US standards. A sandwich with two thin slices of ham, one slice of American cheese, two tsp of mustard, and two slices of white bread has double that... and lots of people eat that for lunch and then go home for a regular dinner. While doing that every day isn't necessarily healthy, it's well within the realm of acceptable for an occasion.
Since you mentioned that you're serving this to your friends, I imagine that this isn't your every-night dinner, it's probably a dinner party. It's supposed to be a little bit of indulgence with which you can strengthen friendships and make memories. If the salt freaks you out, push the envelope a little with your cardio the next day to thank your circulatory system for the modicum of extra effort it put in. While you're hosting dinner guests, however, just let the special occasion be special.