It does not seem to me that all these posts were of any help to the OP. On so may forums there are posts about E rated tires yet very little discussion on the relative application.
His 1999 Tacoma has a GVWR of 4924 lbs. His C rated tires which are likely load index 104 are rated at 1984 lbs each. I don't see a problem with that. The original tires in that truck may well have been P metric, although he would definitely want LT tires. It is a relatively smaller truck with relatively smaller tires and relatively smaller loads. By comparison my Ram 2500 has a GVWR of 8800 and 315/70R17 tires that are much larger than a Tacoma's tire and as such are E rated.
Speaking of smaller loads, Hamer95USA did not note the weight of his camper so how can we make a recommendation without knowing all the variables?
Tires are still available for 15" rims. Just not as popular, but there is still enough of a market out there that they are being produced.