Sounds like you did it like I probably would have. I was not aware of the expanding foam for posts product. Something to keep in mind.
Here's something to log in the back of the ole brain for future projects: you can take odd spray foam projects to some guys' spray foam shops. I've had big tanks insulated via spray foam (for industrial construction projects). We'd ship the tanks down there and they could do a nice job and seal the exterior with a UV resistant rubberizer. They could do it on-site too, but the guys gave me some reasons why they could do a better job in their shop in a more controlled environment. In talking to the owner of the operation, guys bring down small stuff (including hot tubs) their shop and leave it to the side and they can get to it when they get enough for a day or half a day's work, or when something larger comes in (like our tanks). It's not too hard or expensive for them to walk over and shoot some foam on the smaller items.
In your case it would be almost impossible to get them to come by for what you needed, you'd likely need to put your hot tub on a snowmobile trailer and leave it there when they can get at it. So all in all, you did it the right way. But just letting you know how you can have stuff spray-foamed in case you had a future item. I had a wall and ceiling one time at my house where I needed to re-do some spray foam. It was really hard to get them to come out, but eventually they did after a lot of badgering of the owner. I got a chance first hand to see that it was a fair amount of work for the guys to suit up, plastic everything off, mobilize their tools, undo it all, then purge the lines and put everything away. It doesn't pay for them to travel hither and fro for a small job. If you or a neighbor has a compact tractor or skid loader, moving around a hot tub with long forks is pretty easy.