Portable battery charger and jumper/starter recommendations and issue

In a truck camper, weight matters a great deal. My lithium batteries are half the weight of the lead-acid batteries with twice the power since I can use them down to around 10% or more of their capacity as opposed to 50% capacity on the lead-acid batteries. If I were to recommend Maxworld lithium batteries since I have purchased several time, they're a good, safe bet that are far superior to any lead-acid/AGM batteries. Their price good for me too.