Title is deceptive, I didn't DIY the WHOLE harness
Just the lineman's loops!
I finally found a harness I'm really happy with, and thought I'd share in case it helps others. Warning: I don't have a saddle yet, but will likely use this with a sit drag.
That is a Metolius Patriot 1 which is made for the military.
This is a safetech harness so the gear loops are rated for 1,000 lbf break strength. I've heard of others discussing clipping their lanyard to the gear loops, well it works well.
The stock gear loops are dyneema/nylon and sewed into the belt. Well, 1,000 lbf didn't seem quite high enough for life support.
So, I got 25 cm Metolius dyneema/nylon slings (black and white on one side and yellow/white on another, didn't get to pick color) and girth hitched them around the belt in line with the existing gear loops. Those slings are rated for 4,950 lbf (good enough!). So, if the gear loop fails, they back me up.
I betted they would match up, and I lucked out. The girth hitched sling is the exact right size to match the gear loop. I then did a paracord wrap joining the gear loops and the girth hitched dyneema slings so that 1. they would stay together and I would always clip into both and 2. the wrap keeps the loops open for the 'biner. The stitched part of the sling lies vertical along the belt really well and isn't involved with the loop at all.
I chose this harness among the other safetech metolius' because this one is the most adjustable (28 to 40 inch waist and crazy leg adjustment) to handle any clothing, and like all metolius harness you can adjust the rise (leg loop to belt distance) so your harness isn't cutting into you with certain layers. You could save money by getting another safetech because I'm sure the same technique would work (saw one on sierra trading post for $60 brand new).
The belay loops in front are doubled and I just tie into both at the same time for a safety tether (pic at link below is old version with only 1 belay loop).
relevant links
Safe Tech Patriot One is 100% made in the USA and Berry Compliant climbing harness.
www.metoliusclimbing.com
I've used this 5 times this year and it works really well. The only mechanical downside is that the loops are right at the love handles and so aren't the easiest to clip into compared to loops upfront. If someone had trouble with flexibility it might not work, but most will be fine (I always turn and make damn sure I'm clipping into the loop). It is extremely comfortable to lean back into because your back is supported by the entire back of the belt which is nearly 3" wide.
Another downside is price, but given how much money I spend on my other gear, I really don't miss the cash and feel it was well worth it and I feel VERY safe knowing that I sewed/cut nothing and my modification was adding an extremely strong sling. It is an off label use however.