Best Of

As others noted:  Nice Looking Trailer.

Before getting into different modifications. Consider:
 - getting a set of square drive screwdrivers and checking every screw you can find to confirm they are tight and functional; inside cabinets, etc and everything on the outside.
 - Use a voltmeter to confirm the WFCO Power Center Convertor {cabin 12V source when on RV Park shore power & the built-in battery charger}  When on shore power the 12V outlets (battery terminals) should have over 13,2V if the convertor is functional.
 - With known good Power Center Convertor check all cabin 12V outlets and all cabin 120VAC outlets.
 - Trace Battery Positive Terminal Wire;  does it have and in-line fuse or a fuse box/link thing bolted to the trailer?  Did an earlier owner install a 12VDC Battery disconnect switch {might have been a factory option in 2014}.
 - Have or DIY; brake inspection  and wheel bearing grease replacement.
 - Check Tire Datecode . . . if over seven** years consider replacement
        ** tire sellers recommend five years

Have battery tested by local auto supply store.  If bad or very weak a standard lead acid (cheapest), for AGM (a bit more $) might be fine depending on your planned trailer usage before stepping up to a pricey Li-ion.

While your Mods List looks fine also consider:
 - A portable 12V fan until you are ready/sure/able to do a power roof fan.
 - A portable (small) ceramic electric space heater.  A very small one will fully over heat
       a TAB {assuming you have shore power}

Finally, research, read, learn before doing any mods . . . what do you need based on your camping style and budget not what a sales person or even us 'owners' on the forum suggest you need.