the eco wise has been completely reliable and has supplied a constant voltage plus or minus 4 volts. I have no complaints, just wish it would take 2 hot wires instead of just one.That would allow me to use its full capacity of 50 amps. (2 legs)
I think the Eco Wise is probably very similar to the ISB but I only have experience with the ISB.
To have 2 leg 50amp you would need two units as the only ones I am familiar with are only built for one leg.
The ISB website lists a place where their products can be found in Mazatlan . . .
Av. Universidad #206 Loc. 126 Fracc. Alameda, Plaza Galerias Mazatlán. Mazatlán, Sinaloa, México. CP. 82123
Teléfono:
(669) 940-0840
(669) 132-3333
Web:
http://www.mazcomputacion.com.mx/
If they do not have the 4000 they can probably order one and have it in no time. Many stores do not stock items like this because they are relatively high cost and not in high demand in many areas - I think mainly not a lot of people know about them. ISB has distributors all over Mexico so almost any ferreteria or similar store can order them. The store listed above sounds more like a computer store so they may only have the ones made for computers and not whole house units. ISB does make a bunch of other products so stores they list on their website may not necessarily have all their products. But if you go to a ferreteria with all the info from their website to show the store they can probably order one. The 4000 can usually be found for between 3000 to 4000 pesos or between 200 to 250 US dollars. These are not normally items you walk in and pick up off the shelf.
To my knowledge the surge protectors to protect the entire RV can only be found in the US. Smaller RVs with limited power requirements may get by with smaller surge protectors but I don't know.