Need some advice

Usually, when they hit the 5oog mark, is when I usually stop the every 5 day schedule, sooner if they seem reluctant to eat. May just be time to go to every 7 days:)

I agree with trying to offer less. Are mice a big problem to offer? I can understand if all you buy or breed is rats, but some are just more happy on mice. Males don't need to put on weight like the ladies do, thought it is easier for them to fast during mating when they are bigger. Just stick with mice. Give him a week or two of solitary time, don't bug him and just change the water and clean up poop and then try a single mouse. If he eats it, great! DON'T offer another. Wait a week, limit handling or just don't do at all. Offer another mouse and if he takes that, try another. Baby steps are sometimes necessary. You can't force him to eat and the more aggressive you are about it, the more likely he's going to freak out and feel even LESS like eating.
It took me a long time to realize BPs aren't Cornsnakes. Some can be that ravenous, but most can be a little stubborn and picky at least sometime in their lives. I would recommend very slowly introducing rats again AFTER he's eating consistently every week. Do all the scenting things, let the rat live in mouse bedding for a few hours or overnight so it smells mousey, rub it with a mouse. You may have to do this a few times before he trusts that it is food. Sometimes they will happily eat something one week, then refuse it the next. If the rats are more aggressive or bigger than the mice, he might be scared of them. Just take it slow and let him decide when he wants to switch, no pressure. You can't talk to him and explain it's food, so you have to let him realize it on his own! Good luck!!

yea i say switch to every 7 days cuz it seems by your feeding schedule he has ate every other feeding attempt