Do not complicate your real estate investing with LLCs or other such nonsense

I bought a principal residence in 2016 for about $300k. Now worth about $500k, and has a tenant. My understanding is that I can avoid capital gains on up to $250k if I've lived in the house for 3 of the past 5 years. 

Of course, I have a 2.25% mortgage I don't want to lose.

My plan is to create an LLC, contribute $200k to the LLC, and then buy the house for the fair market value of $500k. I would transfer the title through a closing attorney. I would continue paying that mortgage, as I can't imagine the LLC could assume the mortgage.

Is my plan reasonable? UPDATE: Now that I've spoken with an attorney, he thinks the odds of having the mortgage accelerated is low. My CPA is not going to advise being this aggressive. Since I've learned that I only have to have lived in the house for two of the last 5 years instead of what I initially thought, my plan is to just sell the property.
.
Reed answer: Missing in this is an objective. He tells us where he is now but not where he wants to go. Hard to give someone directions when he does not know or tell where he wants to go.
.
He can sell with no gains tax for the reason he says. IRC §121 $250,000 per spouse exclusion. He also sounds like he is trying to sell a house with a mortgage that has a due-on-sale clause. That makes you payoff the 2.25% mortgage at closing. He wants to keep the 2.25% mortgage in spite of wanting to give the property a new owner. You would have to see the mortgage wording to see if it is assumable. Generally, changing the owner while preserving a 2.25% mortgage requires getting away with illegal behavior.
.
Forming an LLC seems to be required in the minds of all REDDIT novices. I never had one in my 55-year career. Here is my article on how stupid LLCs usually are. 
https://johntreed.com/blogs/john-t-reed-s-news-blog/should-hold-rental-property-in-an-llc?_pos=1&_sid=f258495b8&_ss=r

I have no idea why he thinks buying the property in an LLC would be a good idea. Buying a property from yourself sounds like a sham transaction. If you then claim you deserve some good deal from the sham transaction, I think you are mistaken. Generally, the entity would need to have new people not in the first entity to get any sort of new treatment.
.
Keep it simple. Real estate is complicated enough without creating all sorts of additional unnecessary complications because you are getting information from a bunch of REDDIT know nothings hiding behind handles.