This thread was up a few minutes ago but now seems to be gone. I still wanted to post my comments.

It seems to me for those wanting to adjust their cg it is done with a ballast tank up front. Much easier and safer then moving fuel tanks.
Usually only see it on race boats. Only know of it on one recreational Skater and he's a former offshore racer.
I'm pretty sure the Coast Guard would frown on movable fuel tanks. Probably already Coast Guard rules in place covering this.

I had 4 built in tanks and 4 sending units on my 24 which was built for the Mississippi River record challenge. We manually changed tank plumbing valves if we filled all four but typically ran on the rear tanks only. You could go with three tanks each side. You would have a plumbing night mare but could pull fuel from them independently and change your CG by filling different tanks.

I think ballast tank would be easiest and safer.

Did you ever go for the Mississippi run? Before or after Howard Arneson shattered the record with his turbine powered Skater?

No it was built by someone else who attempted it before Howard. It had 4 60 gallon tanks. Ran like a fat pig full of 240 gallons of fuel. Howard smashed the record the next year. I saw him later at LOTO and told him about my boat and that was a mean thing for him to do! We just laughed. He has a poster signed to Pete at the shop that says "how much horsepower can I have and still how to heaven?"

I have one of his signed posters also from a local boat show here. Also have a real good story about following Howard on a fun run! That's for a later date!

I'll be able to move the new removable tanks in my 28. I'm going to start all the way up against the back bulkhead, so I'll be able to move it over 2' forward from there.....

Your boat already has a ballast tank and probably the most proven track record of winning. Why mess with the tank location?

I have a transfer tank in between my two 55 gallon aluminum tanks so when racing you could balance the cat from side to side. In rigging a DW for racing a friend (rigger) had two aluminum tanks made that we could move to change the CG if needed.
I would love to here your story about Mr. Arneson Onetime and more about your attempt on the Missippi Sam.

Cause I simply don't trust the tank liners. My new tanks fit inside where the old tanks are, so I can position them to keep the COG where it was. These 280's won't be on the boat for too long so I'm not worried about keeping the balance perfect as I'm sure it will change with new motors.

You adding the e-tecs you had for sale over on scream and fly? I would like to see what type of results you would have with those motors.