I know down in this area, to sell it commercially you would have to get it to 4 or so. (more)
Buy some citric acid and add it, 1/4 teaspoon at a time, stirring to dissolve and testing after each addition till you get it to the pH you wish, then can/bottle/jar. With all the sugar in the recipe (sugar is a preservative itself when used in large amounts) you probably will not notice a difference in taste.
There is a recipe for tomato salsa that I like, but I don't like the 2 cups of vinegar (and the vinegar flavor) to be added to it, so I make the salsa up with everything BUT the vinegar (or just a little vinegar) and then test and if necessary I do the above procedure with citrid acid after simmering the salsa per the recipe, simmer again briefly, just before preserving. Works great.
If you do a search of pHydrion and order theie roll of pH paper stripping, get the one that ranges from 2.8 to 4.6. It comes in a little case of two rolls which will give you many, many tests.
The following is from my package of pHydrion rolls; I got it last year from my MFP group:
pHydrion by Microfine,
Micro Essential Laboratory, Brooklyn, NY, 11210, USA