When I was doing battery research a long time ago, I remember Rolls coming up as one of the "serious" battery manufacturers. I just now tried to locate some of my old research, but this is all I could find:
PLATE THICKNESS
Plate thickness (of the Positive plate) matters because of a factor called "positive grid corrosion". This ranks among the top 3 reasons for battery failure. The positive (+) plate is what gets eaten away gradually over time, so eventually there is nothing left - it all falls to the bottom as sediment. Thicker plates are directly related to longer life, so other things being equal, the battery with the thickest plates will last the longest. The negative plate in batteries expands somewhat during discharge, which is why nearly all batteries have separators, such as glass mat or paper, that can be compressed.
Automotive batteries typically have plates about .040" (4/100") thick, while forklift batteries may have plates more than 1/4" (.265" for example in larger Rolls-Surrette) thick - almost 7 times as thick as auto batteries. The typical golf cart will have plates that are around .07 to .11" thick. The Concorde AGM's are .115", The Rolls-Surrette L-16 type (CH460) is .150", and the US Battery and Trojan L-16 types are .090". The Crown L-16HC size has .22" thick plates. While plate thickness is not the only factor in how many deep cycles a battery can take before it dies, it is the most important one.
Also, here is what I had for Seattle area Trojan dealers:
4 dealer(s) found:
Battery Systems
MASTER DISTRIBUTOR
105 S. Brandon
Seattle, Washington 98108
United States
Telephone: 206-762-5522 or 800-543-0085
Fax: 206-762-0713
Battery Systems
MASTER DISTRIBUTOR
5509 West Valley Hwy #B102
Sumner, Washington 98390
United States
Telephone: 253-826-4733
Fax: 253-891-4197
Factory Motor Parts - Auburn
MASTER DISTRIBUTOR
3902 W Valley Hwy N Suite#302
Auburn, Washington 98001
United States
Contact: Steve Deitsch
Telephone: 800-791-6580
Factory Motor Parts - KENT
7820 South 200th Street
Kent, Washington 98032
United States
Contact: Robert Dankers-General Manager
Telephone: 253-478-7535
Have you searched for forklift, wheelchair/scooter, and home-solar batteries as well?
Maybe also look at Crown:
https://www.crownbattery.com/crown-battery-electric-forklifts-pallet-trucks or
Concorde (aircraft batteries):
https://www.concordebattery.com/
Good luck.