Weighting options for switching btw steel and aluminum tanks

Ok so i dive a simple hogarthian harness bp/w with a aluminum bp and worthington steel 119 for this set up i need no lead weight. however i have been doing research for school with NOAA and they prefer for me to use there tanks which are alum. 80's Im fine with this i just dont know how to go about weighting myself for the change. Im diving a 5mm full suit... last dive i added weight pockets to my top cam band and put 5lbs in each pocket and was still a little light i cant really cram any more weight in the pockets and dont really want to have that much in there. i was thinking of switching to a steel backplate but then im afraid i will be to negative when im diving my steel tank. also to complicate matters im very leg heavy so the combination of the longer 80 tank tends to throw off my trim slightly. soooo if anyone has any ideas on what would be the most convenient way of switching btw steel and alum. tanks that doesnt involve buying a new seperate rig lol. . it would be much appreciated.

The buoyancy difference between an AL80 and a HP119 is 6-7lbs. I'm not sure why you were light with 10lbs of lead on your cambands.

I usually wear my lead on a simple weightbelt. My scientific program takes a very dim view on large amounts of non-ditchable weight.

sorry i should have also mentioned my rig is set up for fresh water. so its actually an alum 80 + salt water. IDK how much difference that makes but i was constantly finning to stay down at the safety stop w/ ~900psi im my tank. Weight belt would be the easiest but it really pulls my hips down which i already have problems with so im trying to get the weight higher up.

I'd buy a SS backplate. It's not that much more expensive than lead disturbing enough. Adds 4lbs to your current rig. You can get a new SS backplate with a 1 piece harness for $100 ish. Add lead as needed to the belt. Shouldn't be all that much, but a SS plate is a good thing to have around...

Ankl weight around the tank valve. Clip on/clip off.
Might solve your heavy leg trip problem.

I add another 6-7# for salt water (I'm 200#). You could consider a weighted STA for when you have the AL tank and omit it with the steel tank.

+1 to what aquaregia just wrote.

Add about 6 lbs. of lead to compensate for the buoyancy difference between a HP119 and a typical AL80.
Add another 6-7 lbs. of lead to compensate for the greater density of salt vs. fresh water.
You mentioned that you were a little "light" after adding 10 lbs. on your cambands. Perhaps you just needed 2-3 extra lbs.

It might be a good thing to check on your school's diving program rules regarding ditchable weight.

If you are OK with adding more non-ditchable weight, you can use a separate weight belt that "floats" on the tank (positioned in-between the tank cambands). Some rubber bike innertubing can be cut and threaded onto the weight belt to prevent it from sliding up and down too much.

FYI, if you need to do a weight check, do a weight check. First, determine your optimum weighting needs. Second, figure out what distribution of that weight promotes proper horizontal trim (with consideration for having ditchable weight, if that's important).

yeah the ss plate seems like a good option i just am not wild about having to switch back and forth but i guess thats the cheaper alternative. I also did not realize the salt water was affecting my buoyancy that much i figured at the most 2-3 lbs not 6-7 so thats good to know.
Thanks