I have just bought this just to charge the ecoflo £72 with the voucher, I have already got 2 100 w ones on the roof but thought this might provide a bit of extra .YOu can get crocodile clip to cigarette connector premade cables, and an inline fuse holder (you put on positive wire only) is about 3 quid from screwfix + screw. Add a soldering iron and some shirnk wrap sleeve and bob is your proverbial uncle. It'll cost about £8 total (assuming you have a soldering iron and some shrink wrap for cables already). (https://www.ebay.co.uk/itm/25513260...pid=5339023013&customid=&toolid=10001&mkevt=1 for the croc clips to cig socket premade). It looks liek it'll handle 8a, but you will need to inspect the cable used to check on arrival.
Obviously you'll need to fuse for whatever quality wire is in the premade cable (online cable calculators to work out if it can take 8A or not from the diameter/construction of cable).
Should add I'd proably drop the croc clip end connectors and replace with proper ring/appropriate terminals for your battery if it's a perm socket you install somewhere too).
Should add though in HEAVY use, you may be better buying a seperate 200W solar panel, we've found 100W does not cope with recharging a deltra 2 after a few inclemant days.. Despite your huge lithium reserves, ... a 200W foldable may be better as even in relatively rubbish weather like today where it's been cloudy most of day we've been pullling in 50W near all day. These are actually not too expensive but the raw copper cable to extend the cable to the van if you need it (decent quality long MC4 cables) are about 20-30quid.