I haven't lost a spouse, but I do regularly camp and travel solo. Here are my thoughts:
I take my pets (2 dogs, parrot, plus 2 cats as of this year). The pets do ease some of the "loneliness". Dogs are great as hiking or exploring buddies. Cats are great for cuddling and comfort, and make for conversation starters. The parrot is great for having "interactive talk" as they are vocal.
If you can live your life at home alone, then you can camp alone. It's not much different. The parts that seem to be the hardest are: 1) eating alone; 2) not having someone to share the moment; and 3) fear of strangers.
1. This was hardest for me. But when I started doing non-RV travel alone, I either ate out alone or hid in my hotel room eating take out. I found that eating a late lunch rather than a timely dinner took a lot of the "people are staring at me" vibe away. A good book or a game on the tablet let me slow down the meal a bit. And the more I did it, the easier it got.
2. When something exciting happens, it can be a bit depressing not to have someone there to share it. That's where texting comes in. I just send a quick text to a friend back home giving a "the wildest thing just happened!" They text back asking what happened and I get to share the moment.
3. The fear issue is really personal. You have to do what makes you comfortable. If you can't find a solution to make you comfortable, then soloing may not be you.
I have my cameras whenever I'm out. I find it's a great way to enjoy the sights and I can spend hours taking photos without having a companion sighing in boredom.
I've never felt the need to join a "solo group". I have a small circle of friends who will meet up with me once in a while. I just tell them where and where I'll be and if they can come out they do. Like ppine, if I am camping nearby someone, I will invite them out to my campsite for the day/evening.
1975 American Clipper RV with Dodge 360 (photo in profile)
1998 American Clipper Fold n Roll Folding Trailer
Both born in Morgan Hill, CA to Irv Perch (Daddy of the Aristocrat trailers)