Welcome to Pippin and you to HF. I'm sure you will get a lot of good suggestions.
I will share my experience. BUT, I live in a mild climate area of Southern California. If I lived in a severe winter area, I probably would have done it differently. <snip... and not the kind Ricky had
> Consequently, Ricky refuses to use any kind of indoor litter box.
Just one side comment on this one point... I think you got Ricky as an older puppy, didn't you? He was something like 10 months when you got him? From everything I've read from people who have tried it, it is almost impossible to litter train (or indoor potty train) a dog that late in the game unless they already know it, and you are just "reminding" them. Even then, if they have truly given it up, it can be mighty hard to get it back, which is why I encourage people to think long and hard before letting that behavior slip away if they live in an area with bad winters!
Mostly, indoor potty training is something best started with a very young puppy. BEST started by the breeder, at 3 weeks or so when they first venture out of the whelping box, though I do know people who have been successful starting puppies after they have taken them home if they are persistent. And if you want to maintain the behavior, you REALLY need to encourage and reinforce the behavior life-long. I STILL praise all of mine any time I "catch" them using one of the litter boxes, and they are 10, 5 and 4! I've yet to meet a dog that doesn't prefer the great outdoors. I think of it like us using a Portapotty. Will we use it in an "urgent" situation? Yes. Do we LIKE it? Not so much! LOL!
Mine ALL prefer to go outside. They will all use the litter box if that's not an option. (such as deep snow that has not been shoveled off the deck yet, or if we are out long enough that they have to go before we get home to let them out)
Also even though there is pee involved, marking is a completely different behavior. It sounds like Ricky was a "late marker" like Kodi. I don't think I EVER had to correct Kodi for marking in the house. It never occurred to him. In fact, I think he was almost two before he started to mark even outdoors. (and like Ricky, even though he was neutered early, he has plenty of libido... he has tied with girls in heat before I knew that it was POSSIBLE for neutered boys to do that!!!)
But I know of other male puppies who have been marking fiends by the time they are 5-6 months old, even though they have been WELL "potty trained" by that time. The act of marking is a different "thing" in their minds, and needs to be "taught" all over again for those kids. That is true for the girls too!!! BOTH of my GIRLS were markers in a way Kodi NEVER was, and BOTH needed to learn that lesson. Both quickly learned it is not something we do in the house, but they STILL do it outside. It's just a tad less obvious, because they don't leg-lift. They do what is called "over-marking". One HAS to pee (even if it's a tiny squirt) where the other peed. So Pixel will pee, Panda will wait until she is done and pee on the same spot, then Pixel goes back and has to squeeze out two more drops, just to have "the last word". (or vice-versa) Kodi can't be bothered with THAT nonsense! He likes to contribute to "pee-mail" on walks, but doesn't care about getting the "last word" in the back yard! LOL!