Congratulations on your new boat. Welcome to the SBO forum.
Can you ask the former owner what he used, assuming the boat was in MI over the winter months and was on the hard. I suspect you’re going to need 7-8 jack stands.
Are you hauling at a Marina? Do they require you to have your own stands?
An online search for “boat jack stands” will yield many shopping options. EBay to West Marine offer them in various sizes.
I’m guessing you will want something like the 33” to 50” size. Note your draft is the distance from your water line to the bottom of your keel. You’ll likely use a 4-6”wood block to set the keel on. Then you position you jack stand about 18-24 inches below your water line. The 50” stand could come close to ideal.
Here is an image of jack stand placement on a typical 30ft boat in our marina.