I am 100% a dog person and wouldn't even consider living any kind of life that would not allow me to have a dog, so there is some bias to what I say.
To me, the number one question that anyone considering getting a dog, whether or not they have had dog(s) previously, is "What do I have to offer to a dog?"
Most people instead think: "I want a dog who will do this and that and not do this or that and be this thing which I desire."
But that, in my opinion, is exactly the opposite of the right approach. Dogs aren't here for people to use any more than people are here for that purpose. And, just like with people, you will most of the time get out of a relationship what quality you put into it.
The point being, of course, that having a dog is having a Relationship. Not just having an animal.
So I always suggest a person ask him or her self the following:
How much room do I have?
How active am I? Can I keep a large and very active dog who needs a lot of exercise happy? Or do I need a small dog who doesn't need to go far to get exercise and likes to be a couch potato?
How much do I know about training, can I get training help if there are issues, and am I willing to put in the effort needed to train my dog in the way that will work best for our ongoing relationship?
Can I manage a large breed dog who is very strong on a leash and train him or her not to pull me off my feet?
Do I need a dog who will alert me to the presence of others or one who will actually protect me?
If the latter, then am I willing and able to train the dog to be protective without being a danger to anyone?
How much good quality dog food can I afford? (small breed vs large and how much they eat)
Can I afford to create a fund to pay for vet bills and shots and all of the other things that can come up that cost money?
Can I take full responsibility for keeping my dog safe and taking good care of him or her?
How much time do I have to spend with the dog? (Now, living full time in a vehicle, of course, that answer is "almost all the time", and dogs always like that!
I am a dog trainer with some skill and many years of experience and I have helped a great number of people to solve problems they had with their dogs. Usually the problem is caused because the person didn't think it through before getting the dog, or allowed a bad habit to continue until now it is unbearable and hard to change, or they don't realize that building a strong and trusting relationship is the foundation of living peacefully and happily with a dog, and just expect the dog to do what they are told without realizing that dogs need to be shown what is good to do and training has to be done with patience, kindness, and rewards, rather than NOs and punishment.
I don't think it matters all that much your circumstances; if you go about building the relationship the right way and are able to manage the size, energy, and needs of the dog, you should have a dog. Dogs don't need fancy things. They don't need expensive organic dog food, just healthy ingredients. They can be very happy in a small trailer or living in a van or car with someone who treats them well and loves them and puts their needs first. By which I mean, things like no matter how tired you are the dog gets a walk.
Personally, I would go hungry and never let my dogs be without a meal if it came to that. Not saying everyone has to be like me in that way, but the dog is a thinking, feeling, innocent and intelligent being who depends on the person for everything, and that always has to be taken into consideration.
Bottom line: would THIS dog be happy with what I can give to him or her? If you think the answer is yes and you really want a dog then I say go for it, no matter your age or circumstances. In my opinion, dogs are the best companions anyone can have.