Sump Setup

OK i need some advice please,

i have a 65 gal tank, i wanted to set it up as FOWLR but my wife thinks the LR is ugly so i only have about 10 lbs of it in the tank.
i'm running a filstar xp3 filter on it right now with the bio wheel 60 attachment. in the end i will probebly have abig bio load so i want good filtration.

my plan is to run the output of the filstar into a 30 gal tank i have that i want to setup as a sump/wet dry and fuge.

I attached a pic to help

i want to use the filstar for mechanical and chemical filtrationa and the bio wheels and sump fro bio filtration.

so my main question is should i fill chamber 1 with LR, completly submerged with water and then have the water goo to the fuge
or
should i use bio balls and setup chamber 1 as trickle wet dry and then have the water go into the fuge.

i will only be able to purchase about 1/3 LR and the rest will be lace rock due to my budget.

the return pump from the fuge to the main tank will be a mag 5 with a ball valve to control the flow rate

will 20 watts be enought for the fuge, it will have macro algea and mangroves

thanks for the help