Not sure, eh? Depends on what your version of "better sense" is.
It seems that most folks in the troop let the troop pay for their gas money.
This is somewhat common in troops, eh? Splits the cost among kids more fairly, because no matter what da troop there are always folks who do a lot more driving than other folks. The boys just have to build it in to trip budgets somehow (or bring cash).
In terms of your own pocketbook, this is likely da best choice.
just buy the gas myself and submit the miles for a write off
I mostly do this just because I hate dealin' with receipts (and I get out with different units).
It makes budgeting for trips easier for the boys and amounts to a donation by da drivers, and there are a fair number of troops that operate this way. It can mess a unit up if someone who was doin' a lot of driving stops and da new folks want reimbursements. Suddenly all da budgets are off. Also can be hard when gas prices soar. A bit more common in da middle class/upper middle class troops.
A lot depends on your tax situation, but in terms of personal pocketbook, this will never be more than a fraction of your actual costs.
submit for a reimbursement based on miles (used to be $0.29/ mile reimbursement, I believe the last time I knew about that stuff)
Yah, some troops do this as well, eh? I'd say fewer. It's up to da troop. I don't know any troops that are doin' the full federal business miles rate (currently $0.54/mi). Sometimes yeh see da charitable rate ($0.14/mi), sometimes somethin' in between.
Personally I like this for units, eh? Yeh don't have to bog da treasurer down in receipt tracking, yeh just get a list of da drivers and use Google maps for da mileage. It makes budgeting for the boys straightforward.
On da personal pocketbook side, this comes out pretty close to Option #1, dependin' on what amount da troop is reimbursing.
No matter what, in all three of your options you're still askin' drivers to foot da cost of depreciation, maintentance, insurance, etc.