Staining pine (Whitewood) for exterior use
I'm fairly new to woodworking with the exception of a few random projects here and there (headboard, nightstands, etc). I have recently built myself an Adirondack chair from plans I found in a book and a few people have expressed interest in having me make some for them. In order to keep my cost down for my original chair, I purchased all whitewood pine and finished it using countersunk deck screws covered with plugs. I finished the project with Olympic Elite "Mountain Cedar" stain/sealer. Water beads off of it quite nicely, in my opinion.
Now, having said that, I have since learned that pine is obviously not a proper choice for outdoors use (I knew this but was keeping my initial cost down since I didn't know how the first would turn out). I have also learned about wood conditioner, other choices of wood, etc. My question is this:
These interested parties obviously would like to keep their costs down as well, otherwise they would buy pre-built chairs, but they also like this design. I'm wondering what, if anything, I can do to help keep the wood protected without having to step into something like cedar? Will the Olympic Elite work fine or should I abandon the pine and simply not offer the chairs unless they agree to higher priced materials such as cedar (not necessarily cheap in Middle TN.... ~$20 for 1x6x8)? If pine will work (they're sitting on patios/pavers, not bare grass or earth) what would be my best method of sealing/staining? From what I've gathered, you cannot seal over Olympic Elite because it has a sealer in it already so adding marine varnish won't work. What other options are out there for staining/sealing pine for exterior use and what would be the proper process to ensure it holds up? (not forever, but for a few years anyway. We don't get real harsh winters here but we have plenty of rain in spring/summer and the humidity is stupid high).
I know that I need a conditioner first, but then I'm sort of not sure where to go from there because the Internet is full of information, some right and some wrong. Any help is appreciated. Thanks in advance.
Also, I tried searching first but didn't get many results (searched for: exterior stain pine, pine stain exterior, exterior pine stain, staining pine for exterior, and a few others). I'm on my phone so not sure if that affects search results or not. A link to a good posted discussion is helpful, also.