Jame,
What I think you're getting at is a sort of 'Jump-Warp' drive. Does it work like this?
- You want to decouple 'speed' from 'distance' and break the one jump = one week link. So jump2 means two parsecs per week, jump4 means four parsecs in per week, etc. with jumps able to last shorter and longer than one week.
- If you have the fuel you needn't drop out of jump after a week, but 'faster' drives consume more fuel per week . Consider a 100dTon ship with a jump1 drive. If it could carry 60dTons of jump fuel, it could travel 6 parsecs in six weeks by 'paying' 10dTons per week and never leave jump space.
- Conversely, if you have fuel available and the higher drive rating, you can jump faster. Using the 100dTon ship again, this time with a jump6 drive. It could expend 60dTons of fuel and travel one parsec in 1/6th of a week.
Is that what you're driving at?
If so, you've changed the fundamental nature of Traveller's setting. Anything that changes the nature of Traveller's FTL drive, changes Traveller's setting. It can't be helped.
You'll have faster couriers over shorter distances. A jump4 X-boat for example could travel 4 parsecs in one week, travel 2 parsecs in a half a week, or 1 parsec in a 1/4 week on the same 40dTon fuel load. You'll have slower vessels with much longer ranges too. A jump2 Marava with 80dTons of fuel aboard for example could travel 4 parsecs in two weeks with no intermediate stops.
It's sounds fun, but to do the idea justice you'll need to apply it to its own setting. It won't work in the OTU with it's 1 week = 1 jump = 1 to 6 parsecs paradigm.
Have fun,
Bill