I did some internet research and articles I've found all mention the reason behind using turntables which we already know is even cooking. The turntable replaces manually turning every so often. As I didn't find the exact answer you are looking for, if you don't mind reverting to manual turning of your dish, my opinion is, yes, you can remove the turntable and then rotate the dish yourself every so often.
If the spindle that turns the turntable is prevented from turning, it will probably be damaged so I would suggest some lifts for your pan maybe two untreated 1 x 1 wooden dowels that reach to either side of the oven and so elevates your pan OR a dish turned upside down. Here is a link where I did my reading:microwaveovensinfo.co.cc/Microwave_Turntable_Why_You_Need_it.php Contacting your microwave dealer and explaining your dilemma may get you a better answer.
I have a similar problem with my oven being too small for some of my casseroles. The only other answer we have is shopping for a smaller one or going with round. Actually, I think it's a part of a greater conspiracy, the establishment wants us to spend for a bigger oven or more cookware, LOL. One other thought if your microwave is up high like some are, removing a hot, over sized dish for rotation, often, increases your chances of a hot spill and a bad burn. Be careful. Hoping I've helped some.