The better solution for me these 20 years later has been to co-opt the 5 skills from 'advanced' Microlite. In Beacon I've taken a pretty broad approach to how these skills are applied. Physical represents health, training, exercise. Subterfuge is stealth, trickery, guile. Knowledge is knowing and all the skills that come with study and patience. Communication is expression, attention to details, understanding. Survival is the ability to find food and shelter, take care of yourself, the instincts and will to live. They are almost 5 extra stats really, but they are stat levers not simply another measuring stick, and this is why it works well in the game.
Combining these skills with the Strength or Mind is where the characters start standing out from one another. It influences the way they (should be) describing their actions in the game. I liked this mechanic so much that I emphasized it in Beacon. Microlite has a across the board or flat level bonus which is applied to all the skills and actions. It's simple and its a feature of the game which makes it light - but it does tend to make all the characters similar to each other over time. Beacon does away with the flat level bonus and instead puts the bonuses into the level up process. Classes gain in certain skills and players can choose to apply a bonus to one skill per level. This lets players pump up different areas of and it allows for interesting builds coming from the level progression. You can have a fighter who spend everything on physical and is a beast for resisting poisons and pulling acrobatic stunts - or you can have a fighter who is more well rounded and is a good communicator and gets bonuses for dealing with NPCs and military hierarchy. It is flexible.
I really agonized over using the Survival skill because unlike the original 4 skills it seemed to be there just to add wilderness skills for rangers and druids to exist and there was already a lot of ways to derive these from the original 4. However, I realized that survival was not really much different than the subterfuge skill and in fact having some overlapping spheres or imbalanced combinations is OK. For one, it made certain classes possible, and for two, having more skills but less universal skills is good for character differentiation. Adding in new skills changes the game by making existing skills less applicable, by encouraging certain actions or directions for players in game. In some ways it limits or discourages certain existing combinations - like subterfuge will limit certain types of communication such as lying, or survival would encroach on many mind and physical based challenges. In practice however the survival skill took on some aspects of willpower for me, adding a modifier for the 'spark of life' type challenges for example, and so it actually had a net sum increase.
So all that being said, I've still been tempted to add in another skill. I'm going to go carefully here and try to talk through it because it is a balancing act. During the play test I've seen that the Rogue class really doesn't have as much going for it as the other classes and I thought a good way to fix this would be to make them skill boats. Maybe I'm borrowing a page from James Raggi and his specialist class in LotFP here, but it seems right that the fantasy archetype of the Thief really needs to cover a broader scope to include a role for that fellow who is clever and good at things besides swords or sorcery. A character based on stealing is OK, but a character based on solving problems is much better. Theoretically, giving the Rogue class extra skill points to spend means they are more likely to increase things besides subterfuge, encouraging characters that are good at communication (con-men), or knowledge (the sage). Having more non-combat abilities means that rogues would want to use them. I am concerned however that there is not quite enough here to work with once you get outside the sneak (subterfuge) activities. There's no point in pumping skills into knowledge if the party mage is going to have a high knowledge skill anyway. So if you give the rogue extra points then they are just going to pump them into Subterfuge and eventually get +20 whenever they try anything sneaky. That's not what I want. What I don't want is for the skills to become entirely class defining, although I realize that some aspect of this is inevitable. I also know that any new skill is going to direct the flow of the game. If I put in a skill for say - Commerce it will encourage players to deal with money and business - and if I don't make that a common feature of my game, then it's a wasted space on the character sheet. Any new skill would have to address a gap in game activities that you actually want addressed (so no bathroom based skills, and nothing dealing with taxation or writing performance reviews) and not take away from the existing ones. It would also have to be something that could be mixed with the stats in interesting ways.