My take on this:
The 3025 era is a special case because you start out with the equivalent to a +5 vorpal blade, namely your mech. It´s old, it has a history, and, especially, it defines your role in society and social standing. The watchword here is "Dispossessed".
Using rules for scavenging, trading, supply really enhance the feeling of that era. In addition, tread Mechs like charakters, keep track of "battle scars", and so on.
To further the whole era-feeling, consider these options:
- A "real" Mechwarrior should start out with his Vehicle Trait and a Title Trait of at least +3 (Knight Bachelor) because he is in actual possession of his mech, which allows him to buy the Custom Vehicle Trait and the Design Quirk Trait. Further, this character may redesign, rebuild and rearm his mech according to his own wishes / possibilities.
- A character without the Vehicle Trait gains one mech from the "pool" of his affiliation on loan an may not alter it in any way nor has he control on repairs and refits. This charakter should be forced to take the In For Life Trait / Affiliation without gaining the exp for it as long as he uses the loaned mech. Further, some of the exp gained should be spent on the Title and Vehicle Traits until the character owns the mech (and is knighted).
Try staying away from "loot" of any kind. Rather enmesh rules and roleplaying, meaning that "good" roleplaying should enable a charakter to spent exp in the Connection Trait and thereby gain something. Maybe saving the barons´s ass in that one mission leads to NAIS offering the charakter to test-drive one of their new developments for a time, or being loyal to Liao leads to a Star League-era weapon mounted to your mech during the next routine maintenance ....
Further down the time-line, there is the clan invasion to consider and it is an good example for all of this. Characters in good standing with an affiliation are outfitted with clan hardware, from simple equipment to whole scavenged mechs.
Also consider this: Battletech charakters are larger than life.
Unlike traditional fantasy rpgs, where you start out as a lowly runt, clearing out the beginners dungeon and having to fear the town guard, you quickly move way above that level. Take a look at one of the Turning Point supplements: The battle for the fate of an entire planet in 5 - 8 tracks... That´s the size and scope to aim for and frankly, "just loot" can possibly only stand in the way to archive this.
How about this: Keep size and scope large, then hand out bonus exp towards title, connection, rank as a reward and see what further roleplaying can bring out of this.