Gorgeous rockwork!

Yes, if you use wire fencing or trellises in front of the fence you can grow Clematis.

Here is a picture of someone using wire trellises in front of a solid structure to grow Clematis. This was taken when they were first planted. They now cover them.

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Your height restriction could be a problem, there aren't that many short Clematis that will climb without being tied on. Taking purple out of the mix will reduce your list too.

Piilu has been an outstanding short Clematis for me. Helios is yellow but it is a good one too. Alionushka doesn't climb well but fits your requirements. Juuli doesn't climb at all but also fits. You'll have to tie her down.

You can use the Clematis on the Web to see pictures and do searches. Type III pruning is easiest, whack to the ground every early spring.

Here is a link that might be useful: Clematis on the Web

I just noticed my mis-spelling, sorry!
My husband did the rock work,the trackhoe almost hit the house trying to get the big ones in.:)

I really like those wire trellis! They are not to bulky but look nice! I dont mind purple, I would just have to try to limit it I guess...Yellow is a good idea. I did some reseach on the web, what do you think of this list so far? They are type 2 however....would that work? Or am I off base?
Pilu, Bourbon, Rosemoor, Niobe, Rebecca for red-ish
Mrs N Thompson, Multi Blue, for blule-ish
Josephine for pink

If I loosley tie them to the trellis would that work?

None of them mind the cold and snow, however I would stay with type 3's to begin with. In our low humidity and dry summers I find the 2's harder to grow. Do you have low summer humidity where you are? I'm assuming so because you're in Utah. Also it sounds like you have wind, that can cause more of a problem with 2's.

I can't tell you how many 2's I have put in and lost. The only conclusion I can come up with is they don't like lower humidity. I am now replacing almost all 2's with 3's, there are so many good ones out there.

They will grow fine in the 12" space you have but they do need plenty of water.

Katie

I agree - lovely rock work, and I like how you've planted into it as well as on top.

I find many of my type 2's are killed to the ground by wind and/or cold in the winter, so they only bloom once, later in the season. I also find that they are not as easy to grow as the type 3's. Niobe has never thrived for me. Of my type 2's, HF Young, Daniel Deronda, (both in the blue/purple range) and Guernsey Cream seem the easiest. I also have found that the type 1 Attregene group clematis do well for me and are easy. I grow a couple of blue-purple, and also Albina Plena which is white.

I don't have many not-blue and purple type 3's, but I love Ville de Lyon, a 2-toned pink and reddish. It rambles through shrubs and up a fence for me, but its larger size might require some guidance on your part to encourage it to grow sideways rather than only up each year.

You could also try some of the Texensis and Atragenes scrambling DOWN the wall :)

Type IIs can be slower to get established and more difficult than Type IIIs though Piilu is a II it behaves like a III. It is just outstanding. Daniel Deronda is also outstanding for me.

Only the Integrifolia group would need tying. The others will cling to wire on their own.

Petit Faucon, Alionushka, Gazelle, Juuli, Harlow Carr, and more are Integrifolias, type III pruning and long blooming easy to grow.

It sounds like I will be planting 3's due to the snow/cold weather I get. I was worried about that. But it looks like I still have options. I am going to do some reseach on what you have suggested.
Going down the the wall is an idea.....hhmmm.

Is it getting to late to plant this season?

I have noticed some of the sites describe them as "free flowering" is that the same as long blooming?

Thank you so much for all your help. I would have bought the wrong plants and been so dissapointed. If you have any other suggestions pleas let me know. You guys are awesome!

I believe that free flowering means they have a lot of flowers at one time rather than long blooming. Bloom times and length of time do vary.

I live in Minnesota (zone 4) and never had any problems with snow or cold, even with temps dropping to -30F. I now have over 100 clematis plants, most of which are type 2 that are doing just fine, so I wouldn't limit myself based on the cold climate. Type 3 also tend to grow much taller than 2s, so unless your fence is 8-9' tall or taller, type 3 might not be a good choice.

Here is a link that might be useful: The President in my yard

I'll add a comment as well in support of type 3 clematis for high altitude arid climates such as Utah and others in the Rocky Mt region. Relative humidity is often in the single digits and I have far better results with them.

Here, they also do better on the eastern side of support structures - buildings, fences, etc. The afternoon sun is just too much once the summer gets going.