It's not that LiFePo4 can't be pushed through Absorption and all the way to 100%. It's that it will affect the cycle life. Stopping at 90% is better.
Here is how I see it:
1) Buy that van.
2) Get $30 re-settable AH meter from Ebay or Amazon.
3) Measure your actual 24 hrs draw for a few days. Some devices you've missed out, and some will draw less than you think.
4) Estimate solar harvest in your area.
#3 and 4 is called Energy Audit.
5) No matter of the results, oversize your solar by 30-50% or as much as the van roof allows.
6) If the audit results and available roof area don't look good, plan for good alternator setup and possibly genset.
7) Decide on battery bank and inverter.
Li batteries will still be there after you've done all these steps, maybe they will even cost less then.