The quick answer to a question of credible sources for solo trekking trails is, "NO", there are no sources which can be completely relied on for this kind of information (at least for the western ghats part).
The following set of attributes might help you in deciding upon heading out solo in the western ghats:
The western ghats are safe for trekking. I haven't come across any trail which can be classified as "dangerous" in terms of the danger from robbers/people etc. However, some trails are relatively riskier than others (eg Agumbe trek) due to the naxal threats. Poachers are a danger in densely forested trails(But I guess you are not venturing into these). There is very little threat from animals while on the well established trails. Off beat trails around thick forests are riskier due to elephants, snakes and poachers.
Summers have an additional threat of forest fires. The forest departments do put up the fire lines. However, as the recent incident indicated, the grasslands are susceptible to large scare forest fire and can cause fatal injuries.
Grade of treks:
Most of the well established treks in the western ghats are of easy-moderate difficulty. The only one that I consider mildly difficult is "Kumara Parvata".
All the treks in the western ghats are accessible through a nearby town/village. These places are cost effective and people are very welcoming. The chances of being coned are lesser than what you would find in the northern part of India.
When to trek the western ghats?
Do not venture during monsoon and summer. Summer heat is intensified by the thick forest cover and monsoons are just uncomfortable due to the heavy rainfall.
Camping and other facilities:
On some of the trekking spots, camping is not allowed. This is mainly because these spots lie in the range of a reserve forest or a sanctuary. Some of the trails might require you to get a permit from the forest department to even enter the trails. Some trails might require guides. Water, although available in the form of streams is not completely reliable. A better option would be to carry water purifying filter. None of the trails have facilities in terms of proper camping sites. It's entirely up to you how you setup your campsite.
Always remember, in case you get into trouble(either due to an injury or an animal attack), the exit routes on western ghats are difficult. Two reasons:
- The forests are thick, facilities are less.
- The general health facilities in smaller towns and villages are not that well developed in India. (Most of the trails lie closer to the villages and towns than the well developed cities).
Finally, do remember that there are loads of blogs on the net which can give you information regarding the trails. But whether to trek solo or not is a purely personal choice. If you are okay with being alone on a hilltop/forest with no civilization nearby, western ghats are pretty good (Always keep in mind that, in case you get into trouble, most probably there is no medical evacuation by air). You will find trekking groups, but very few camp out (most of the trails can be done in a day).
EDIT: Route for Agumbe trail:
- Safety: No threat from locals. Locals are friendly and welcoming. This is a naxal area. Possibility of encountering wildlife if trekking solo (mostly snakes).
- Grade: Moderate. (Some sections are steep)
- Accessibility: From mallandur, the peak is around 14km away(shortest route). You will need a guide if trekking from Agumbe side. The forest is very thick and there are multiple routes(none of the trails are well marked). Route from Kigga side is well marked.
- Forest permit: Required. Recommended to have the contact number of an ANF official as well (Anti Naxal Forces).
- Camping: Allowed at the top. No need to carry excessive water. A flowing stream and a well are available at the top.
- Exit routes: None. You'll have to trek back to your starting point to get to any human habitation.
Wrote about the itinerary we followed: Agumbe trek. Might help.
I've added additional info on the possibility of forest fires in the western ghats.