Marine electrical help needed

[Adventuren1]

I am installing a 500 amp Victron Smart Shunt on my 1990 Bayliner 3288. The existing wire mess needs cleaned up and moved to a bus bar. I understand basic marine electrical and know that the shunt needs all the loads going into it etc. My question is about the existing 200 amp class T fuse and whether it goes before or after the shunt? My other issue is properly connecting the negative lead to the bow thruster. Currently the loads on the battery are on multiple posts instead of drawing from each end to balance the draw. The bow thruster leads are both on one end of the bank. I believe the bow thruster is too much for the 200 amp fuse so I will route the 4/0 negative to the opposite end of the bank. So my plan is to use a separate bus bar for the bow thruster to relocate it to opposite end of the bank. I believe the breaker for the bow thruster is 400 amps. I do not need to measure that load with the shunt so I can bypass the fuse and shunt. Also, I am looking for a certified marine elec. tech. to come do a survey of my boat. All referrals welcome.