The attached screenshot shows the route of the proposal, in red. The black line shows the original route.
The route from West Bay seems to follow the River Brit all the way to the north of Bridport before turning to reach the original line.
From Loders the track bed is a permissive path as far as the Powerstock Common nature reserve. It then passes through private land as far as the Cattistock Road bridge from which it is a public path to Maiden Newton station.
There was another proposal railway in the 2000s
https://www.dorsetecho.co.uk/news/1768145.one-mans-promise-to-build-light-railway/I would like to know the understanding of the potential passengers.
Normally, there is a half hourly bus from Bridport to Axminster, thence hourly to Dorchester and Weymouth which is quicker than the intended rail route.
In the 1880s, the Bridport Railway was concerned about connections at Maiden Newton and proposed running powers over the line to Dorchester. The result was the extension to West Bay and the doubling of the line to Dorchester, with the development of West Bay as a tourist resort. The connections at Maiden Newton would still be a problem unless they are looking at a tourist railway but with modern traction.