I am happy with my pair of Tenergy 12.8VDC 10Ah LiFePO4 batteries and have used over a dozen larger 12.8VDC LiFePO4 battery packs from batteryspace for other projects with good results too. I called Tenergy in California and these Tenergies do have the under and over voltage protection built in. If you shop around, you can get them on special with chargers included but a constant voltage power supply works fine too.

The weight is nice, the charge cycles are awesome, how long it holds its charge is really awesome and the steady output makes a big difference for radios and such. They dislike freezing temperatures more than some other options if that is an issue.

You can use your trickle charger (as long as it doesn't have an auto desulfate mode) but it is not the best idea for reasons listed and explained on here and all over the internet. Also, these are LiFePO4's so you can blast them to a charge in no time compared to a lead acid.

I wire them to the glider with inline fuses and the same connectors that I have on my chargers for convenience. Then I cover the terminals with hot glue and make handles with packing tape as my glider is a very tight fit for two 10Ah batteries. You can pull them out by the wiring (not recommended) or the slim tape handles (recommended) when needed.

LiFePO4's are starting to get very developed and produced by some bigger manufacturers so it is pretty hard to go wrong as long as they fit and meet your power needs. There are some good discussions and links on doing a power budget for your glider around too.