The wish list continues

I’ve already posted in the past a few of the things on my “wish list” of equipment I will need to make being in the van even more liveable. Last year during the summer and fall months, I could only get a couple hours out of the deep cycle battery, which I have learned is certainly not normal. I then discovered that the isolator between my starting battery and the deepcycle was shot, and one of them was dead, and drawing its power from the other. So, in an effort to provide myself more power, and prevent that from ever happening again, here’s my list (hyperlinks on a few):

New batteries – I need to buy new batteries to replace the damaged ones, this is a must. I’m borrowing a deep cycle from a friend right now, and he’s going to want it back.
I also want to buy two extra deep cycle batteries, for a total of three deep cycle batteries. That will power me for a long time. I’d like to get AGM batteries, but they are very expensive. I need to house these inside, so they’ll be housed in boxes that are ported to the outside, under each seat, as I have a rediculous amount of room under each seat for some reason.
Smart Battery Charger – I can’t afford solar panels right now, and I do want to build a much stronger roof for the van as mine is purely fiberglass, and weak, so solar on there will eventually crck my roof, if not just come crashing down. A “smart” battery charger is far better for deep cycle batteries than a regualr one as it “Automatically switches from full charge to maintenance mode“, and won’t overcharge your batteries, thus decreasing the life of your batteries. Depending, I might see if it’s possible to just leave this hooked up permanently. If so, I’ll buy as many as I have house batteries. Thoughts? Is it possible without wrecking the battery?
Since I will have three “house” batteries, and I don’t use a lot of power, for more than basically, just my laptop, and stereo (which is wired into the house battery, not the starter battery), I won’t be drawing a lot of power. I can hook up once a week at a friends, and charge the batteries while I am at work. Heck, If I wire it, I could plug in at the parking lot daily, and charge the batteries.
Hydrocaps – These help with the outgassing and loss of water in wet cell batteries. I’ve read a few reviews, and it appears they very well could be the answer.
Continuous Duty Solenoid – After the isolator crapped out, and I lost TWO betteries, I’m not taking any more chances. This solenoid will prevent such a situation from ever happening again. What happens is that when you turn on the key, power goes to the solenoid which activates a magnet inside it. The magnet lifts a bar which makes a connection between the two large posts, allowing charging current to flow from the starting battery to the house battery. When you turn the key off, current no longer flows to the solenoid, the magnet turns off, the bar falls and there is no longer a connection between house and starting battery. That means that if the engine is running, the house battery is being charged, and if it is off, the house battery can not run down the starting battery. (Source)
These, my friends, are my top priority now. Get the power stable, and then on to the other list.
Any ideas on things I could be missing?