I have been using a simple dual battery isolator from ARB and that died last trip. Had it for 10 odd years so not bad. I still use lead acid batteries for both so don't know if it is worth the $300+ cost of the new Dc to DC chargers now a days? Only $44 for a voltage sensitive isolator that switches to both being charged after the main battery reads 13.2v.
http://www.ebay.com.au/itm/VOLTAGE-S...YUYHZHg882v9bA
I have noticed also that my 260w solar panel is not keeping up as well as it used to. Be about 6 years old now and maybe just loosing efficiency as still powering the exact same fridge and led light strip. One thought I had was to prolong its life is to get a better solar regulator for it. One of the MPPT type which would give 10-20% better output depending on conditions. Is a cheap Chinese one better though than the cheap PWM only type Chinese one that is already on there?
http://www.ebay.com.au/itm/LCD-30A-M...QAAOSwA4dWMHQI
Otherwise looking at something that will do both things and known high quality from Redarc like this maybe. Plug unregulated solar power straight in.
http://www.ebay.com.au/itm/REDARC-BC...oAAOSwEK9T0Mhy
Or the Ctec which works out a bit cheaper and the same setup I think.
http://www.ebay.com.au/itm/CTEK-D250...gAAOSwCU1Ym~R1