I have a 40' MD on my 88 and being light on the back end has never even came close to being and issue. According to MD website there is less than 500 pound difference between a 40 & 45 so weight is not an issue. Unload auger length will be. I have the extender on my 88, with the 40 ft head I can unload on the go pretty comfortably. If I get where the header is in line with the tire on the cart you need to be on your A game. With a 45 I think a man will need to be stopped to unload and you may not be able to hit the center of whatever you are dumping on like you want to. There are products out there to get the auger long enough to make it work, just not sure what the auger itself can stand for the added length. Be interesting for someone to try it and see.