Welcome to Class B Forum OldGit.
There are two Pleasure-Way specific forums that might interest you:
http://autos.groups.yahoo.com/group/Ple ... nersgroup/
That said, I really hope that you stick around here.
Sounds like you'll have some interesting projects to share.
A recent 6volt vs 12volt topic is here: http://www.classbforum.com/phpBB2/vi...hp?f=12&t=2464
My van is plugged into grid power whenever I'm home. Continual maintenance charge. The converter/charger in my van is somewhat "smart". Automatic bulk, normal and maintenance modes. Coach and chassis batteries are all maintained together through a manual selector switch in my rig.
I used to use BatteryMinders for that task. My two BatteryMinders now maintain other batteries in my garage. Backup generator for power outages, lawn tractor batteries etc. I like BatteryMinder products and think their solar charging product would be good. I have 120 watts of solar panels on the van roof that would maintain my batteries but I park it in my garage.
You might find this topic interesting if you plan on extensive electrical upgrades: http://www.classbforum.com/phpBB2/vi...hp?f=12&t=2123
Need someone else to help out here re: suspension, air assist springs, anti-sway bar, front end springs, shocks etc.
The lack of roadway clearance when it comes to waste plumbing is a fairly common complaint with Class B's. Would you gain an inch or two with the suspension upgrades you are considering? Maybe your van is sitting a bit low.
I do not recall ever reading about the modifications to the waste plumbing you are considering. Moving the black tank might be difficult unless you can see a way to extend a pipe. Usually there is very little space to work with under a Class B. The black tank (or a part of it) in my home-made campervan is immediately below the toilet. The toilet flange is threaded and it screws into the top of the tank. Yours might be different.
The black tank might actually be in two parts. A small tank immediately under the toilet coupled to the main black tank.
Have fun with these projects and I hope to see more posts from you.