Wow! I was thinking about getting a trailer in August I didn't know you could put that big of a tank in one of those. Very impressive. Depending on how much it's is to relevel it should be worth it to protect your investment
The tank is 210 gallons? Unless the floor is a concreate slab it is not able to carry that kind of weight. What you are seeing is the floor joist sagging which will probably get worse or fail. My floor was started sagging my 125, so much so the bottom plastic frame on the bottom edge cracked. After releveling the stand to reduce the stress I hired a foundation company to come in and pour footers, jack supports, I beam and double the floor joist. I was then able to put a 180 in its place. A 210 plus sump weighs close to 3000 lbs