A saddle like the Cobb JOF55 or Dash Strike.9 might not decrease your measured setback a great deal, but they will put a more usable portion of the saddle further forward. They also might facilitate increased anterior pelvic tilt. You could run one of those within 1-2cm of the Arione for measured setback, but remarkably different positions would likely develop. Of course you can "perineum-sit" the forward 2cm of the Arione, but even for limited use as you suggest, that could effect your performance if it is pushing you back, rotating you back, or just generally painful.

An aero road bike can make a damn fine fairly steep time trial weapon, but attention generally must be paid to getting the rider forward and rotated enough, and getting the bars low enough. Go figure.

I have a very lightly used Arione Tri (came with my tri bike), which is 10mm longer than the standard road Arione with a more cushioned nose, which I'd sell for $40 if you'd like to try it.

I can get low.

I managed to find a "new old stock" Giant stem kit that works with my steerer tube that's silly negative stem slam. The Propel's do not have the weird larger steerer tube the other Giant bikes have. I'm guessing due to the aero headset stuff.

But, thanks for the advice. Given my budget attempt this year, I'll try to see what I can find in classifieds or ebay for those saddles.

I'm going to pull the classic internet forum move of not answering your question, but suggesting another path.

Consider doing the TT on your road bike setup, with no equipment changes. You'll still get the experience of doing a TT: proper warmup, timing of everything, pacing, holding your best position. But you'll do it without the distractions and unnecessary expense of buying saddles & clip-ons, then spending time installing and tweaking them. The position you wind up with will most likely be sub-optimal, and guys on TT bikes will have an advantage anyway. So just do the TT on your road setup so you can spend the bulk of your time and energy worrying about the important stuff rather than messing with equipment.

An added benefit is that you'll be training your ability to ride fast, solo, on your road bike, which is useful for lots of things.

Forget about the result as well, the goal should be to execute the best time trial you can (in terms of power, pacing, etc.) on that day, and to be able to identify later what kept you from doing that if you don't. In other words, the goal is to learn to do a good TT, and also to see if you enjoy it. Adding in equipment changes just distracts from that in my opinion. You can add in the "fun" equipment decisions later, once you're a proficient athlete at time trialing. But quite frankly that stuff is a hassle and a waste of time if you're just learning to TT.

FWIW, I've been riding a TT bike since the early 90's, but I do a few road bike TTs every now and again just to remember what that's like (most US amateurs did not ride separate TT bikes in the 1980's when I started).

It's a bit too late. I got some stuff on sale, I'm about $150 all-in on skinsuit, helmet, and clip-ons. I'll use the skinsuit anyway in road races or CX races. I used it this past weekend in a race. So if you look at it from a perspective of TT only equipment, I'm in just $75.

FWIW, I've enough power in that time range to be competitive in my category if I can get my position just "decent". I also already train with intervals that would be useful in an ITT.

It's not trying an ITT once either. It's a series of 6 races. Then there's now also a local TT series popping up. So I stand to do about 10 of these this season.

To me, I can go hammer for 20-30min anytime I want without the clip-on's. The position is kind of critical to the discipline in these days.

OK, fair enough. Sounds like you've thought it through a good bit.

check out the new SMP Tri saddles, I am demoing on TT bike and am so suprised.