The only difference between the 2500 and 3500 as I understand it is the leaf springs in the back, which gives you about an extra 400lbs. We have the 2500 which has about the same loading capacity as our 83 b350 did. Check the sticker inside the drivers door, it will have all that noted there.
For the 2500 non extended, you get ~3800lbs to play with. That includes you and your wife and everything you put in it. We are almost finished with our build and I don’t believe we are even close. You certainly don’t want to max that out and you can upgrade the suspension to the 3500 specs if you really need too.
Careful of modifying the the suspension. That is the one thing that will void our warranty.
Make sure you get the lumbar seats or factory swivels if you can find them. If you get the suspension seats you can never add swivels.
You’ll definitely want the backup camera. I’m not sure if that is standard or not.