sounds fine. as you say it's not like he's going to be left in there all the time. and he will probably be quite comfortable in there, a big bacyard can be quite overwhelming for a little puppy. i think thr rspca have a lot more to worry about than that, which i think would be a non-issue anyway as he won't be in there 24/7 and will have shelter and water. i wouldn't worry hun, just enjoy your new addition, he sounds gorgeous!