I'm doing that with my L3000 and it's all it can handle. I bale my own hay and have to cut my baler down so the tractor can handle them. If the bales you get are really 1200 lbs. I would lean toward no, it won't do the job.
I assume you are talking about 4x5 bales. If so I don't believe even if it will pick them up you won't have enough lift height to stack 3 high.
I'll tell you how close I cut it with mine. I worked with my baler on size and density until I got the biggest bale my tractor would lift. They are about 4 x 4 1/3 and my density is set on 875 - 900 psi.
I baled beside another baler that rolled 5' wide x 3.5' tall bales. The windrows were about equal and if we started at the same time I could actually go farther than he could before my baler was full. Another words I feel like my bale had just alittle more hay in it. When we hauled them out I could pick my bales up without any problem. Tried to move one of his and couldn't even get it off the ground. Even though the total weight was almost the same the extra leverage of a 5' wide bale instead of a 4' made enough difference that I couldn't handle them.
Hate to be long winded but I was trying to give you enough info to possibly help out.