Keep in mind that a smaller trailer doesn't mean less gas costs. The frontal area of a travel trailer is the major factor, and weight to a much less degree. So, our Minnie is 26'9", but there are longer trailers out there that have about the same dry weight. With the two of us, we're happy with our downsized trailer...use to have a 29' Sunline. I wouldn't have a smaller trailer without a slideout. If we didn't have the slideout, I'd want something around 29-30', and I wouldn't want to have anything longer than that to minimize problems with campsite selection, rv parks, navigation around fuel pumps etc. (my choice....others have no problems with 32-36' trailers.
But with two dogs, I'm not sure if I would be happy with our Minnie as floor space is limited. I think you have to look at a lot of trailers and see what you think will work for you. How you use the trailer will make a difference also. We're retired, so we take longer trips....getting ready to head out for a 6 week trip. If you only plan on shorter trips, smaller spaces even with 2 dogs may not be a problem. And, if budget is an issue, you have to get something that will work with your tow vehicle.
As you look at trailers, consider where the dogs will spend the night and can you easily move around the trailer. Also consider the impact of bad weather and having to spend more time inside.
Minnie 2351DKS Click on 2351DKS floorplan
A floorplan such as the 2351DKS looks like it would be an option with a couple of dogs, and towable with a 1/2 ton truck.