My opinion which will only cost hundreds of dollars. Esp sense your space limited is a lifepo4. The only real issue is the cold weather charge, and they are light enough to bring inside over the winter. ( i will link everything below )
Do you do cold weather camping? if so disregard everything I say below.
The amped out doors lithium battery I linked to is about the same physical size as you 35 ah but weighs 14 lbs ( from generic sizes found online ) but has 4 times the usable capacity and 4 to 5 times the life expectancy. It will take care of its self when charged properly and stored properly. What that means is unlike lead batteries which want to be stored at a full charge, lithium like 50 to 70% charge. They will put them selves in a sleep mode when not connected to a charger or load. They are very happy this way. Now you do want the proper charger for them, and due to the cost of the battery I dont recommend a cheaper charger. The victron one I linked to here somewhere is $121.
The other issue is if you charge while plugged in to the car/truck you need a battery to battery charger, as the lithium will take every bit of charge your alternator can put out. The amped out door battery will happily take 50 amp charge rate, your alternator in your car will happily give that until it cant any more and it dies trying. I am not providing a link as there are many options and some are very expensive. but there is cheaper options, like using the same victron charger and a small inverter in the tow vehicle.
So buy the amped outdoor battery, proper victron charger ( which is blue tooth so you can check on charging on your phone ) then the battery monitor so you have a battery fuel gauge that tells you how much battery is left. Then buy an anderson plug set for 10 bucks thats good for 50 amps then you have an easy to unplug no tool needed to bring inside system.
Side note, sense the lifepo4 batteries have many many recharge cycles ( thousands ) being able to bring it in side and use it for back up power is a nice option. Imagine being able to run your fridge for 8 to 10 hours from the one battery, or your laptop for days. Or if your a cpap user for 2 or 3 nights. I might have posted this already in this thread, I ran a 500 watt halogen work light for 1 hour 22 mins of the amped battery.
https://ampedoutdoors.com/collections/b ... es-capablediscount code "RXAngler" cost after code iirc $324
charger $121
https://www.amazon.com/gp/product/B07TM ... UTF8&psc=1battery monitor
https://www.amazon.com/gp/product/B07CT ... UTF8&psc=1anderson plug set
https://www.amazon.com/Mr-Brighton-LED- ... ljaz10cnVldisclaimer, I have no connections to any of the above stores or seller and anything.