Your research is correct. Staining pine any color is difficult not to have it come out blotchy. So here goes;

First, the most important step to get a even finish is the sanding. The finer you go with the sanding the less blotching you will get. Start with 100 grit, working your way up to at least 280 grit, not skipping any grits in between. (100, 120, 150, 180, 220, 280). Use high quality sandpaper, not the junk sold in discount stores or the cheap brands in big box stores. Don't try to stretch the use of it. When its not cutting anymore get a new piece. You must sand all the nooks and crannies, not just the easy flat parts.

Second, seal the pine. Use Zinsser's Seal Coat

Sand again with 220 grit to knock down any raised grain.

Third, stain. Apply with a rag, don't brush on and wipe off. Too much stain is going to make the blotching worse.

Fourth, seal again with seal coat to prevent the finish coat from reacting with the stain coat.

Finally, apply your top coats. Use oil based finish, not water. Apply first coat, let dry, and sand with 220 again. Wipe off all dust with a damp rag and apply another coat. Two coats should sufficient, if you like the look. If too rough, sand again, and apply another coat.

Lots of work, but that's what is needed for a high quality finish. Go to a good paint store to get your products, not the big box stores. A good paint store will also be able to give you good professional advice. This is a lot of work. If you are not up to it, get a pro to do it. I would recommend a finish shop. Even some painters aren't capable of doing this.

One last warning. Clear finishes have a short lifetime outdoors if exposed to a lot of weather and/or sun. They will never last as long as paint.