Eric,

A once-a-week shampoo is just about right. Less is better.
You could try a shampoo for fine & fly-a-way hair.
That should give it an extra coating to make it more manageable & protect it from drying.
As I said in another thread, you might want to consider a deep cleansing shampoo thats clarifying to remove product build up, once a month or at detachment time.

I know what you mean by wanting to rinse it in between shampoos.
Some leave-in conditioners build up really quickly and can make the hair 'crunchy'.

I usually give my hair a good rinse in the shower when that happens or better still, dampen it well with a water sprayer/spritzer and comb it through with a fine tooth comb.
I use a 'nit comb' (pic attached) and this really gets to the individual hairs and combs off the product. Its also great if you accidentally get a bit of glue stuck in the hair. A bit of solvent and a comb through with this stops the hair forming a clump.

Once again I'm going to recommend the Tigi conditioner I've mentioned before.
If I do soak my hair under the shower, I often use a dabs of it whilst the hair is damp and you can immediately feel the difference in the texture of the hair.
Combs & brushes glide through the hair after applying it.

Hope this isn't information overload!?!

Best of luck.