Can't add much to previous post. Lifeline site has their charging instructions.
Don't know the Xantrex monitor you have. I use my Trimetric for voltage and amps readings during the recharge. I set my charger to 14.4v and leave it at that setting until amps get down to 0.5/100. Then zero the AH counter on the Trimetric, which gets off kilter over time. Then adjust the charger to 13.x Float voltage.
Does your conversion have a converter? If not you should get a PowerMax LK 60 amper which has adjustable voltage setting and is over that 51 amps.
A 60 amper will need a 2000w gen to run it if you are off the grid. However, charging to full off grid using a gen is not practicable for gen time to do the 90-100 part so just do a 50-90 and then solar. Do get some shore power at least once a month and do the full recharge to 0.5/100