Installed many a system, engineered, pumped, static, switched. Maintain many. Finishing one today.
Lee said the inordiniate elevations of the leach field inlet lines might be okay. That is not good advice unless you have a set of engineered plans with a "switching" distribution box spec'd in. That entire fake D box has to GO, [okay on edit I see a reasonable quick solution]
But I would have had a real D box set in a base of concrete installed, or a huge bed of compacted gravel. Nice cast d box here is only $40 with a lid. Quite smaller than that mess you have [ had] now, and square.
Real D boxes come with adjustable 4" solid drain pipe entrance caps [spin adjust] . Or you may adjust inflow with careful trimming of the inlet nipples with notches. You should convert that junk flex pipe OUTSIDE the box and bring solid nipples inside, and make sure all lines are fed EXACTLY the same. Do careful observation and an adjustment after a few frosts.
I believe you can exclude the lint and sediment as an issue, unless you have a garbage disposer. If you have a split chamber tank, and a correctly set "T" shaped outlet line, and no disposer, I find after repeated tests that a 1200 to 1500 gallon tank can go 5 to even 10 years before sediment starts to get deep on the bottom. If you have the money and LOTS of kids, every three years is overkill but safe.
After 35 years of perhaps everything hitting one line, that field can be totally bio-slimed to a point where nothing will percolate properly, especially in wisconsin. The installers were obviously not pro's.
VERY RARE to need a filter unless you are pumping into a pressure sand bed filter with small distribution lines, with a short standard leach field on outfeed. Filters on standard systems are not needed or wanted by our septic inspector, and he really watches the D box, even checks them for level. Bad d boxes kill systems. Mine all have easy access risers and lids for quick and do-able inspection.
You are on the outside anyway for septic systems at 35 years.... so say some engineers.
I do like your multiple filter set up - good idea, but it might be a few decades late. And who wants another chore mucking in the Sh*&^ every few months. Enough trouble comes my way without having to pay for and install it.
Sorry for the hard line, but eventually you might need to muck out and re-gravel that over-used field. And you probably know this, but master plumbers in [at the least] California dont know a whit about septic. They give special licenses for that.
Good photos and information here altogether...
On edit - saw you are using only 600 gallons a week. If the installers used that junk pipe and that fake "D" box, without leveling the pipes, Sherlock says they also cheated on trench depth, length and gravel.