To go with my comment above:
Happening to me even though there's space at the foot of the bed. 😛
Still there as I'm passing back through going the other way- actually found him in survival mode this time. Helped by my remembering where he was last time... and his potion wearing off. Saw him drink a new one too. Other then that it was just following the sound and frantically right clicking the air. 😛 There does seem to be a viable path from the portal, but I reiterate that I haven't been on the overworld side of it in ages.
Doubt it- I haven't been in the chunks on the other side of that portal for at least a couple of weeks. Unless there's some weird chunk loading rule involving Nether Portals I'm not aware of... Are both sides of the portal loaded when you're nearby in single player?
PS: Now that I think of it, I should probably mention he wasn't there the last time I passed through to go fix my tools.
Home base and grinders Portal Wandering trader Worksite
<----------- ------>
There you are. Just below and to the right of the Bee.