It's what you make it. Many people share small spaces to live and/or play and do just fine.
With that, here are some questions to help you find your answer:
When you say "camping", what do you mean? Do you mean staying at traditional campgrounds and spending your time doing outdoor activities? Hiking, swimming, etc. Or do you mean staying at RV parks and sightseeing in the area? This could have a bearing on the other questions below.
How much time do you intend to spend INSIDE the TT on a regular basis? Do you plan on being in the RV whenever you are not out doing something? Or do you plan on hanging out outside unless the weather is bad?
How do you spend your time now? Do you each spend most of your time in a separate room from the other? Or do you spend most of the time in the same room?
What do you want to do when you're inside the RV? Do you want to watch TV? If so, do you watch the same shows or different shows? Can you read while the TV is on or do you need quiet to read?
Do either of you have habits/quirks that drive the other crazy? Does he nap during the day and snore? Do you tap your fingers when you're bored? etc.
Personally, I have no problem sharing my 21ft C with a friend (plus 2 dogs and a parrot). We spend most time during the day outside. If it rains, we come inside and talk, play cards or dominoes, etc. It's tight when we're fixing meals, but we make it work.
A few tricks I've found that make it easier:
1. Everything should have a dedicated place. If you have to move the lounge chair off the bunk bed and into the shower stall so you can go to bed; and then back to the bunk bed so you can take a shower; etc., you're going to get tired of it. I have very few exceptions to this rule - three items: popup canopy which I only bring for specific trips when I know it will be set up and used; folding table which I only bring for specific trips when I know it will be set up and used; and a set of dog steps which stay on the bunk bed during the day and get set up on the couch at night so the dogs can get in and out of the bunk bed. Everything else has a dedicated spot.
2. If it hasn't been used in a year, out it goes. No "but what ifs". For "emergency gear", I use the "if that breaks, can I still make the trip work?" rule. That goes something like: "if the fridge breaks, I can use a cooler and buy some ice to make it through the trip" - don't worry about fridge parts while I'm camping; "if the engine breaks down, then I'm stuck where I am" - keep some tools and parts to do basic repairs.
3. Get back to basics. People managed before microwaves and hair straighteners and entertainment centers. It's not that difficult to do without those for a week or two. That saves a lot of storage space and by not having to have a generator, you gain THAT space to store camp chairs, etc.
4a. If you have "sometime guests" (like the grandson), keep a set amount of space reserved for their stuff. Do not fill that space up with other things when they don't join you. Keep it empty. That keeps you from adding stuff you don't need because "there's space" and keeps you from having to find space whenever they join you.
4b. On the same theme as above, try to keep 20% of your storage space empty at all times. This gives you freedom to rearrange or add an occasional item (following the "if not used in one year, out it goes" rule).
5. Use packing cubes to keep things "confined". Instead of a junk drawer, put all that stuff in a small packing cube. It keeps those weird little objects from getting lost, etc. Use them for clothes - you can fit more clothes in a smaller space using them and keeps everything from falling out when you grab a shirt.
