Man, I'm surprised there was room for your balls on that Big Honda, much respect for such a horrid trip in horrid conditions! You've now got a real beast to enjoy!
St1300 is a great bike wish they still made it. Years ago one of the guys at work was a Goldwing fan and was going to buy another one and I told him to look at the ST1300. He wasn't fond of its looks but once he rode it, he bought it and loved the bike better than the Goldwings (or the BMW which he traded in). Only thing he needed to do is get handlebar risers since the bars were too low for his liking. Good luck with this bike, I'm sure it will run for many many miles
The Honda ST1300 is a really excellent motorcycle. Check the fuel requirements for the bike. I believe the early ones were premium fuel bikes. Definitely change the coolant and the oil to start your proven maintenance cycles. Forget the gas mileage. Now you have a mileage making machine. These bikes can easily go 100,000 miles with maintenance. Make sure it's fuel injected, if not you. may want avoid ethanol gas if you can or use Stabilo in the gas to protect the carbs from ethanol gumming. You can't assume anything. You are lucky to be able to deep dive the internet and see any potential issues with the ST coming your way. Congrats on getting an amazing motorcycle you could easily go across the country in sporty comfort tomorrow. Please give us a 'my new to me ST1300 video'.
Love my ST1300 - only been riding it for 16 years and it still ticks off all the right boxes for me. Long distances on any bike in really cold weather can suck. I've got the add on deflector kit so I'm a little better protected from the wind than stock.