woody's right, that's one way to do it. Sometimes you'll find that if/when you pull the anchor as far back as it will go, it will balance much better on the bow roller and the weight of the chain going down into the locker will keep the anchor on the roller without assistance, except of course in boisterous conditions where you'll want to tie it off.
That said, we had exactly the same issue of only a single bow cleat.
http://c34.org/bbs/index.php/topic,4457.0.html
Scroll down for pictures. And please read all three pages.
What many of our skippers did was add one (or two) MORE bow cleats. I added only one on the port side shown in the pictures in the link. Some made the mistake of taking out the original centered BIG cleat and adding two big ones on the port & starboard. I find that center cleat PERFECT for holding the anchor rode when anchored. I also found the single added poprt cleat plus the OEM center one just fine for berthing: I use the center one for the starboard dock line.
Your boat, your choice.
Just figure out access to down below (they were able to access the stanchion bases, right?) and add one or two cleats, keep the big center one, and you're done. You may have to cut a hole in the anchor well wall down below, so buy a round or rectangular Beckson port and add it for access.
This is a problem the builder should have figured out, but many, many didn't. You're not alone, but the problem has been solved by folks who have come before.
Try this, too:
http://c34.org/bbs/index.php/topic,5064.msg51112.html#msg51112
Good luck.