I'm doing the same, going 24V, and have found two Shurflo 5367131 24V Extreme Freshwater Pumps (used) off of eBay. Only took two years of looking for them to come up for auction and I think I paid $60 to $75 each of them.
I've got a Vitrifrigo with the 12/24V Danfoss compressor and I think the inverter module runs a little cooler on 24V, keep it clean and cool and they last a long time - let them get dusty or without at least some fresh air 'chimney' type air flow its an expense repair. I've also got a yachty built-in BD50 unit salvaged as a spare.
I committed to 48VDC for renewable energy systems a little too early - now am stuck piecing together 24V.
I did find a boost 12-24V 3-stage battery charger, made to install near TV battery, (The better to keep line losses down) for charging while towing or emergency top-offs when boon-docking. I'm also using its 24V quick-disconnect at the A-frame as input for portable solar panels.
Thirty-feet-plus of 4awg
at 12VDC & 40 amps is 5% wire run losses (one advantage to having batteries on A-frame, they're closer!) but my batteries are going above the axles, So I can reduce the wire size to 8AWG.
After all is said and done the alternator-charger-battery wire run will be nearer to 40 feet and I'd hate to use anything as heavy as 2 or 4awg beyond the built-in trailer circuit!!