I wore a drysuit. My three friends wore wetsuits. I was warm the whole time and rarely hot. My friends seemed comfortable during the mid-day, but were cold in the morning (putting on damp wetsuits) and afternoons. Drysuits are much more expensive than wetsuits and are more easy to damage by abrasion. We did this trip in early-March, when it was not hot. When we do the San Juan River this late April, most of us are taking drysuits, but it may be warm enough that we don't wear them all the time.
The spray skirt (on your waist) and spray deck (on the boat) are used together. I wear them if there are rapids that splash water up into your boat or if it is particularly cold weather. This is both to keep you warm and to avoid having to go ashore to drain water out of your boat too often.. We didn't have either condition on this trip. And we anticipated that we would be getting in and out of our boats alot for shallow water. It takes a minute or so to reattach the spray skirt to the spray deck each time. All of this logic assumes you are also wearing a wet suit or dry suit and that the weather is not hotl. A spray skirt, spray deck, wet suit or dry suit may not be needed if weather is very hot and you don't mind being wet, but I don't have much experience with these conditions (being from Washington State). Also, if you have a self-bailing packraft, there is much less need for spray skirt/deck, unless the weather is cold.
I just started paddling with a guy who uses a self-bailer ... without a spray skirt or spray deck, even in winter (he wears a drysuit to stay warm). I don't have any experience with these boats myself, but my fist impression is that they would be a good option for front-country whitewater-focused day trips, where you might want to push your whitewater limits a bit and not need to stop to drain your boat and deal with that pesky spray skirt all the time. But I still lean towards closed boat with zip on/off spray deck for multi-day wilderness whitewater (my passion), where you don't typically push your limits, and for an extra measure of warmth.
Many of the side streams run clear. We each carried 10L and a 4L dromadory bags. Pretty sure we found good water at least every other day, so maybe we didn'tneed that much capacity. We used a 1 micron pre-filter while filling the bags from the creek to minimize any sand particles, then standard water filter when transferring from dromadory bag to water bottle, or just poured from dromadory bag to cook pot if boiling for a meal.
I just got back from a 200 mile bike packing trip through this country. We hiked along this river too. I believe your packrafts are Alapacka Expeditions?
