Welcome to the Hi-Lo community
Assuming that your Silverado has a V8 engine, you could handle at least a 22 footer, you might be able to handle more depending on other factors of your tow vehicle, but you'd be fine with up to 22-23.
Do you know what series your Silverado is, 1500? 2500? You'll also need to have, or add, a trailer brake controller, trailer hitch, and a transmission cooler is a great idea too. With 3 of you, and hopefully 4 (hubby), you will want to have some sort of truck bed cover, as you will need the extra storage space and the cover will keep your gear dry and safe. It's highly recommended to have a weight distributing hitch, but don't buy one until after you find your camper, because sometimes they will sell the WDH with the camper.
Bev and I really admire that you're going to take your kids camping, it's one of the best family activities there is. Have you ever taken the kids camping before? If not, you may want to rent a camper for your first trip, kinda like a test drive. I doubt you can find a Hi-Lo for this, but you could easily find a pop-up. It's a cheap way to check things out. DW and I rented one for our first "camper" experience. We had only tent camped until that. We loved using the pop-up, but we wanted something more substantial, and with more comforts, so after much research, we bought a Hi-Lo and we love it.
Louisiana has a great Hi-Lo club, it would really help you to hang out with these folks, you'd learn a ton, and have a really good time. One of our most experienced members, Sam Shields, is a member of this club. Here's a link to their information.
Please ask all of the questions you want. Campers are very friendly folks, and none are happier to help you then the ones in the Hi-Lo community.