Need more battery capacity

[Steveva]

Recently returned from a 70 day outing. We saw some temperatures in the middle 30's so we used the AC heat pump. Had to use shore power everyday due to CPAP. Need to get away from shore power. Our old van had two AGM's and water was our limiting factor at two maybe three days camping if we watched our usage. This van has one AGM at 64 amp hrs, size 24.
The CPAP is rated at 90 watts and I'm thinking 10 hours run time, but usually less at 8 hours. We are also adding a compressor refrigerator. All our lights are leds as installed by Pleasure Way. I really don't want to rewire the house part of the van but if we increase our battery capacity are some of our current wire sizes under sized? If we switch to Lithium Phosphate how do we charge the batteries?
We currently have a Surge Power Industries battery separator which (from their manual) will assist in engine starting and protect the charging system.
We also have a Intelipower 9200 power converter. Which I am assuming will be replaced with something similar to charge the Lithium batteries. We also have a 400 watt inverter which we have never used. We seldom use the microwave. We may use the microwave when traveling and then we start the generator (usually at a rest stop) for a warm lunch. One suggestion is to get a large Lithium bank and charge it at home before we leave and then occasionally as needed use shore power to recharge, don't use the van to recharge, and dump the generator, and get an invertor. I don't see that as a viable solution, I would sell the van and buy newer with all the engineering work done by the manufacturer. Of course then we would have payments.
With the old van our routine was set up camp and then bike or hike and maybe take a drive but we never had an issue with battery capacity. If needed we used the drive as an excuse to charge the batteries. We would like to get back to this routine. I am thinking 200 amp hrs would get us there but do we really need that much or will 150 amp hrs do it. I have started a kw hr per day estimate but am wondering if I should continue as I am thinking others on this forum may have a very good idea of what we need from their own experience. I, at this time do not have the time to install solar but may in the future. We have a 2011 Pleasure Way Excel on the Ford E350 with the V10. Thank-you in advance for any suggestions and help, Steve