No problem. Just wire them in parallel.
Actually, I use an 8-position fuze block for my Caravel--two of them for the batteries. Then I can just pull a fuze (automotive flat type, easy to pull) when I want to disconnect one battery and only use the other (sort of an early warning system, or a usage rate indicator when I'm boondocking--then I have a good estimate of how long the other one will last).
Anyway, just remember you aren't starting a car with these batteries. You can use #8 or #10 wire--makes installation much easier.
One note of caution: If you're going to parallel your batteries, they need to have the same condition, eg, same use, same age. So you really need to buy two new batteries and install them together. If you don't, the less capable battery will quickly "damage" the other battery and you will get much less life out of it than you expect.
Your charger can handle both, if you have a modern charger. If the charging current is high, the charger/converter will self-limit the current. It only takes a few minutes, like one or two, for charging currents to drop down to the 20-30 Amp range. If you're concerned about max current, you can pull one of the fuzes and charge each battery separately if you've run them both down to a low level. If you discharge your batteries separately, you should charge them separately. I don't separate mine very often--too much to remember, too many steps to get right.
Remember, going below 20% charge significantly increases the chance you will damage a battery. I try to stay above 11.5 volts under load, but never below 11 volts.