The skimmer you should put after the trickle filter....Although why you running a trickle filter in your sump for that large of a tank? With how much
LR and other natural filtration that you will have you will not need a trickle filter which are generally used for bio-balls.
IMO i would not even use the trickle filter. I would run a seperate tank for a refugium that would then filter down to another tank for your return, and protein skimmer, also
UV. The skimmer pump should only be used for the skimmer not for return, you will want the skimmer to run at maximum effeciency with the pump that the manufacture recommends.
with deticated pumps for each I still need a larger return pump? around the 3000gph range?
Personally i would have one large return pump for the sump, and T it off to other locations in the tank. Also you might want to consider doing a closed loop system for that large of a tank, that will give you the water flow you will want, and not have to have the ugly look of
PH in your tank. Any other questions feel free to ask. Heres a good website i recommend that you look at:
www.oregonreef.com
HTH
Garrett