Good Morning SeaSea, welcome to THP.
Congrats on your salsa business also! Sounds a lot like my salsa operation. Where I live is a remote, isolated valley. There are only 3 food stores and one organic food store within 40 miles. I don't supply the health food store. We've tried it and the people who shop there want organic, which I don't do, and the store is small enough that customers usually shop at the regular food store anyway, so if they do want my salsa, they buy it there cuz it was .50 or more less. I've been doing this about 25 years, almost 20 years here in the valley, so I have a pretty good feel for how sales go at the different stores.
My operation does a production run of a full batch about every 7-10 days in the summer and once a month in the winter (Feb-Mar-April). SOMETIMES in the winter, if sales look to be reaaally slow, I'll do a half batch. I don't like to do that because I have to pay the person who helps me the same amount whether it's a full batch or a half batch.
I leave the salsa in the stores right up to the pull date in the winter. If your stores have room for some back stock and are willing to stock the shelves for you, I'd move the delivery out to at least 21 days if you can. That's if you have a good enough feel and tracking of sales in the stores. I don't have anything on the label that says "expiry" or "best by", I use a simple Monarch price gun and just put numbers on the back of the tub "05/28". From experience, I know the salsa is good for at least 6-8 weeks before it starts to ferment.
On the run we did a week or so ago, we did a full batch even though the stores still had some left over. For one store that usually takes 100 pints, they had about 30 left. I just gave them a credit on the new stock and marked the old stock down to half price. The old stock was all gone within 3 days. This was the first time in about 2 years where we had leftover, it happens.
For testing- I'm assuming all your sales are local, none across state lines and no internet sales. Your licensing should be completely done by your state agent, whoever did your initial licensing. They are the ones to talk to about what they require for a longer shelf life. My initial licensing was 25 years ago and I'm sure regs have changed. There may be some classification that allows 45 days without expensive shelf life testing. Your inspector would be the one to talk to about that.
To start with, I'd suggest taking a little bit of the salsa, blendering the snot out of it to get it a really smooth puree, let it set for 24 hours and then do a pH test. If you don't have a decent pH tester, ask around for one to borrow. What you are looking for is the 'finished equilibrium' pH of the salsa. Blendering it helps the acidity to equalize through all the vegetable matter quickly. Think of making pickles...the whole pickles have to sit in the brine for 2 weeks for the vinegar to penetrate all the way through the cucumber. Sliced up cucumber chips will be pickled in a couple days. Smooshing it all up allows a pH test quickly and also gives a homogeneous sample. If you test the chunky salsa, the sauce will be more acidic than a chunk of onion, and what you want is a test of everything in the salsa.
You may find that the salsa has a finished equilibrium of around 4.0-4.5 pH, which is good. With this information, talk to your inspector. He/She may make a determination on the spot that the salsa is OK to go 45 days. Or they may want the salsa to be tested by a food processing lab for a proper shelf life test or pH test. Maybe adding just a touch more acidity to the salsa might do the trick.
Sorry I don't have any more specifics regarding shelf life tests. Please keep up posted on what you find out. Not a lot of people make refrigerated salsas. Kind of a niche market. I know what you mean about being the only fresh salsa on the shelf. It cracks me up to see other salsas using canned tomatoes and with a pull date 6 months out.
Good Luck and again, keep us posted.