Over the years we have camped with an assortment of RV's.
We had a TC with 2 kids..11 months apart. We started with them at a year old camping. I will say two words...never again!!!!! Not with small children. We did in another TC when they were teens and had their own tents.
In my opinion a TT would be better. Think not only storage but rainy days. You also need your space. When you have another small baby think of the extra items you will need.
Only you can decide but think realistically. Think not only about what you want, there are others to consider, including your dog. You can always do the TC when there are two of you again.