I know its important to have matched batteries if running them in parallel.
Are there the same considerations if they are in series, say 24V.
Would it be OK to line up a 110 Ah with a 130Ah?

Yes, it will be OK to run the different amp hour batteries in series for 24 volts, BUT! It's like a chain, it is only as strong as it's weakest link, in this case, once your lower AH battery starts going down, your voltage output will decrease incrementally. On an average day of fishing, you likely won't see an appreciable loss or drop, but if wind and waves are above normal and you use your TM an extended amount of time your likely to see your power decrease faster than you would if both were the same higher AH rating. I'd recommend matching them if you can, but if you can't for a while and both batteries are presently in good condition, you can run them without any big issues.
Hope that helps!! Tight Lines!!