In reply to KB3UYT:
Like Roy, 20m wouldn’t be my choice for such short range. I’d be looking at specifically setting up and using NVIS antennas. The bands to consider are 80/60/40m. I’ve found 60m in the UK to be particularly good for giving me coverage over 25-400miles. That’s using an inverted V dipole with the apex low, about 4.7m AGL. I don’t use 80m so I can’t comment much on the band but 60m is badly affected by D-layer absorbtion during the Summer. From October to April it is very effective for QRP SSB working. At the bottom of the sunspot cycle it gave excellent inter-G coverage when the skip was far too long on 40m.
I would suggest that you probably want to consider full size antennas at these lower frequencies rather short antennas with loading coils.
The other band I’d be looking at is 2m. Either FM or SSB. I’d expect to have few problems working 0-500miles with 10W of 2m SSB and a 13-17ele beam to similarly equipped stations. So a 150mile range with a few watts of 2m SSB and a small beam is not unreasonable especially if you’re well located as you will be on a summit. 2m SSB is no longer as popular and find stations with beams and rotators will be less common. You still find plenty of fixed stations with a vertical antenna, probably a 2/70cms antenna possibly with some gain. A vertical beam will again allow considerable distances to be worked on FM or SSB. Of course, a small PA will do wonders on 2m if you can carry the batteries and PA itself.