you know op, pictures would possibly lend some weight to your creditability here.
lots of other makes and models of vehicale of similar years have rust issues in that area, i mean its not a known issue to everyone including 15 year olds for nothing... that was one of the first few things i learned when shopping for cars avoid the ne and check for rust on the under carrige...
and as to why your 1995 ford doesn't have the same issues, that's like wondering why your wife got the flu and you didn't this year, just chance and luck to a certain extent, the tacoma issue was with the frame rotting from the inside out where owners couldn't do preventive maintenance, here whats happened is you got a rock chip or managed to scratch the frame some how expose the bare metal and over time just got eaten away, so who's to say your ford hasn't gotten luck, do a search for the for ranger rust issues of the same year (the f-150 is a boxed frame as opposed to a lighter truck's c-frame design like our toyota's compare apples to apples at least)
best thing you can do to keep you trck from rusting out is to wash it regularly and visually inspect it every few months, i usually check it out when i'm doing an oil change, i mean your there already right....i have no problem going through a car wash when it's grey and snowing out just for the mere fact to wash all of that packed up crap off the underneath...in my mind it's better to wash it off and let it repack up every few days then let it sit all winter, i park outside so sometimes that asty snow/grit/salt combo can stay under the truck for a few weaks just working its magic...
again it's like anything it will last as long as to how good you take care of it, meaning even the cheapest pile of crap can last 50 years if it's well taken car of and the most nicest well built item can be destroyed in a matter of minutes if not taken care of properly, and personally i admit i only take care of about 65-75% of the stuff i should do at any given time, it's alot of work man, seriously pull out the manual and tell me the last time you did half the stuff they tell you to do right there in the book, i know i don't...so should i get mad at toyota for not doing everything i should? that's like getting mad at the dentist for getting a cavity, nobody brushes and flosses after every meal like they should, at least i don't lol, twice is good enough, lol, i hope your starting to see my point...
and letting toyota know about it in the way you are could
cost them money just by having to respond regardless of right and wrong, and the parts are expensive enough as it is.
bottom line your aware of the issue now, fix it ,keep an eye on it and maintain it ....