You can access Baldy Mountain if you purchase a Weyerhaeuser permit https://recreation.weyerhaeuser.com. You will need the “Longview – St Helens” one. The permit is valid for a year and gets you a map that you can load into an app on your phone as well as a key to the Recreation Access Gates.
I approached the summit from the “Zillig” Weyerhaeuser gate which is on Zillig Road. To get there you can Google “Zillig Road WA” and it will route you on I5 to exit 36. Take a hairpin sharp right turn and head South on Old Pacific Hwy, then take a left on Rose Valley Road. At the fork with S Goble Creek Rd, go right to stay on Goble Creek Rd, and then another right when you get to Zillig Road.
Usually the Weyerhaeuser roads are pretty well signed, but not in this area. Once through the Zillig Gate take road 6150, then a sharp left to stay on 6150 and as you get closer to the summit you will need to take a right on 6150 E. You will need your Weyerhaeuser map for this one as these roads are not on most topo maps.
I posted summit pics to SOTA Atlas. There is a large turnabout at the top which can shelter you from the wind which came if very handy on the stormy day I summitted. Plenty of options for antennas on this summit. I was in a cloud when I activated so not sure about views. I had 5G data service from ATT on the summit so was spoiled to be able to use my SOTA Goat app to spot and track other Spots. In addition to having cell service, I found ease in getting into Vancouver, Portland, Oregon City, and Beaverton with 2M FM.