for self-support gear, there are lots of options to keep things light and simple.
for a group, the eco safe boom box will handle 4 people for a week. just line with a new wag bag each day to keep 'er tidy. makes a great foot brace.
alternatively, a climber style poop tube with rv caps will pack in any boat.
fore firepans, there are some cool DIY options like The Fire Pan | Self Support Kayak Camping
but you can also just use a steam table pan Amazon.com: Standard Stainless Steel Full-Size Steam Table Pan - 4" Deep (24 gauge): Kitchen & Dining
(or a radio flyer wagon pan I hear lol)
Drinking water is often best snagged from a side stream. but a little pee in the river isn't the problem. Ag runoff or mining activity/mineral load can be though.
I like to use a simple gravity filter, made by sawyer Sawyer 3-Way Inline Water Filter - Free Shipping at REI.com
I use it with a filter bottle on the water during the day, and in camp, the same filter gets hung with a 1 gallon bag. I got all the water I need while I set up my tent. whole package weighs about the same as a traditional filter like a katadyn hiker. Add a prefilter as needed.
people do months in the backcountry on 5lb packrafts. others haul 300lbs for a one night trip. any of these boats will work, and I personally find a single IK is just fine handling my 250lb ass and all my gear for a week, including a groover.
the critical part, as always, is actually getting out on trips.