Maybe it is too late by now, but I have the Kromski. I have not used an Ashford. The Kromski folds and travels in its bag (good - we all use them in my class so we can do homework.) The Kromski also has a warping board built into the back, so you don't need a separate item. I recently made two warp chains that missed the center four stripes of color in my planned warp. I was able to put one chain on, notice that I was not going to have enough ends, see what was missing, flip the loom, make a third chain with the missing portion, flip back and finish my warping. It was a long day, but I did not have to commit an angry person's axe murder or shrink the width of my shawl. It would have been easier to have a separate warping board, but they go for $100 or so, so I am happy not to have bought one. Either way, get a stand. Don't try to use the loom with tables, they are never quite right. Enjoy
I had to make 11 identical squares for class. The first square was released from tension and measured and compared to measurements under tension. I repeated the measurements under tension for the next ten.
I used a tapestry needle to put in a piece of yarn every two inches (they were only 11 inch squares.) This worked pretty well.
I am not sure how fine "quite fine" works out to be, but I am guessing you need more fiber. To do the math for the yardage you need:
Width of scarf x density (dent of heddle) x length of scarf x 115% (you always lose some length and width when you remove the scarf from the loom.) = warp
You may also loose warp length if you use a loom (Almost 1 yard for each time you dress the loom on a basic rigid heddle that you might borrow. That gets added to length of scarf along with any fringe you want to add.)
The weft is trickier - there is a rule of thumb that I am forgetting... (2/3 of warp?) but you may beat so that the scarf is light and airy or tightly woven.
When I knit a scarf from mohair that I had spun, 4 oz. made a decent sized scarf. I wouldn't go under four and I would probably want more. If you spin very fine thread, you will have to set the warp strands close together (dpi will be a high number) or the scarf will be too loose.
A high-end loom with a very skilled weaver might be able to get around all of that, but I am not in possession of either. If you are planning something like a peg loom, start to do the calculation of how many times the yarn will have to cross each dimension. Yes, weaving requires math. There are computers today because there were weavers yesterday.
Can you stripe with commercial? Or use other fiber? I ply expensive fiber with cheaper fiber to stretch the quantity sometimes. (Exquisite hand-dyed with plain undyed works very well. You don't muddy the colors.)
You can even add a spacer between picks of weft (or blocks of weft) such as a pencil or straw or cut piece of paper (long and skinny is what you are looking for). Slide it out later. Now you have a large loose area. Depending on how you treat the fabric and what else you have done it may start to even out over time, but if you felt wool or use leno or some other non-plain weave stitch you should get the empty spots to stay in place. (Tie rya knots or spanish lace or...)
Try to be sure you see light in squares when you look through the fabric on the loom if you want more drape.
Betty Davenport's book on surface weaves using Rigid Heddle should be fairly doable on your loom. (Maybe not all...) It is a revamping of an older text that hadn't been printed for a long time. One class of weavers at the weaving studio I go to is working through them and the results are quite lovely.
A few of them are making a belt using the sampler techniques.
When you are using it, make sure you find a comfortable spot (even if you have to get a stand.) You will weave stop weaving much sooner if you are slightly uncomfortable (and may not specifically notice why.)
Heddles are measured by dents per inch, which is the slot in between spokes and the hole in the spoke both. Most that you see commonly are 8, 10 or 12. If you look at a specific project that gives a fabric you like (more like a rug, a towel, a scarf, etc.) you can see what yarn they use and try the same. Yarn.com (webs) sells weaving yarn and is pretty good about making it plain what you use the yarn for.
Sew over the end of the scarf now, before attaching anything and knot the fringe as close to the scarf as possible and cut that fringe off since you know you don't really like it. Then if you still want to work on the scarf...
You might want to attach goofy floppy flowers or polka dots or such with safety pins, just to see if you like it more with the color blocks broken up. (Crochet or knit or fabric applique or ribbon?) Yellow bumblebees? Or you can lay down cord/yarn and see if you would like it to be couched along the surface of the scarf. You could have a secondary geometric pattern to echo the blocks or a loopy curve to completely soften them.
After you decide if you are going to add color to the body or not you can trim the end, silk or velvet or fur or lots of fringe hooked in with lark's head knots. (Since you don't want to add trim in the wrong colorway.)