yes. It is not rocket science. Adjusting a one piece harness is not the end of the world. Properly adjusting a one piece harness is easier than properly adjusting a stab jacket, mainly because a stab jacket can't ever be adjusted properly. It is cinch and pray.
One piece harness is literally this simple. Loosen the shoulder straps, put the rig on, have your buddy hold the plate against your back and snug up one side at a time until you can get a fist between your chest and the shoulder strap. Once both of those are done, close the waist belt so it sits properly. Adjust the crotch strap so it doesn't pull the waist strap down. Move the D-rings to just above the nipple line on the shoulders, and put the left D-ring right at your hip bone. What's so hard about that?
If it has a chest strap it is exactly the same procedure as a stab jacket, or better yet, a backpacking harness. You don't go to expert backpackers to put a backpack on, the Transpac/Transplate adjusts exactly like a hiking pack, and fits the same, and if you use something like the DR deluxe harness, it has the chest strap so instead of having the lower cinch straps you just tighten via the waist belt. Don't make a simple process out to be harder and scarier than it is. The OP has already been spooked once, no need to do reaffirm that.
Transpac is a back inflate BCD. Similar to other back inflate BCD's which can be used off the shelf. Easy peasy, a good choice for a new diver, we agree.
One piece harness, D-rings, tri-glides, backplate, tank straps, crotch strap, webbing, cut the webbing, burn the ends. Brand new diver, assemble and adjust everything by yourself looking at internet pictures, videos and words written on the internet. Then travel and do your 1st dive with your wife. What's so hard about that ? For the average Joe and Jane who just came out of class ? I guess we disagree.
You do know there are people that ask their friend to assemble their Ikea furniture for them because they cannot do it themselves.
It probably would make sense to create a new thread to continue this debate.