You can do it with a high CYA / high chlorine pool . . . if you have reasonably reliable circulation equipment.

If you'll look at the Best Guess chart, in the 60 - 90 ppm CYA range, you can run your pool up to 20 ppm on Sunday PM before you leave, and it will probably be around 5 - 10 ppm when you return 5 days later on Friday. PoolChlor of California and Arizona has been running 10,000's of pools that way since the late 60's. They use chlorine gas (CHEAP!!!) and ~150 ppm of stabilizer.

However, they have the routine down, and you don't. You will want to be completely sure you DO have the routine, before you kick the service guy to the curb. That probably means paying him for 4 weeks when you don't need him . . . just to make sure he's not needed.

You WILL need to supply info on your pool, so a recipe can be worked out. Before you start, you'll need to supply
1. A reasonable guess at your pool gallons;
2. Info regarding your pool surface;
3. Info regarding your pump and filter;
AND
4. You'll need buy a K2006 series kit. I'd recommend the K2006C, since you going to need to test your stabilizer levels more than the 6x a plain K2006 can do it.