Not knowing exactly what your looking at my first thought is auxiliary battery would need fairly heavy connectors & wiring. Access to plug in charger (or solar panel w/controller) could be quite a bit smaller.
If Palamino has 'port' that you think would work for both Id contact them. They may offer source. There are a lot of remote battery charging/jumping posts available.
remote terminals..Sources on
EbayDifferent types of quick connects
quick connect
Pre made panles bit expensive. IT may be simpler to hard wire an Anderson connector for the aux battery. (or other type of plug rated for use)
powerpole-accessories Found this pic on www.truckcampermagazine.com/news/tcm-exclusive-2014-palomino-rv-announcements
Nice panel..other than the box, remote battery posts linked above. Think Id want it somewhere protected, definantly a kill switch and fused. Lil overkill for connecting solar or external charger.
For small solar panle simple 2 pin SAE connecector would work, or low amp charger (not for battery) similar to
SAE connector