Question Bubblebum for one trip with a 4YO

Im trying to decide what to do tomorrow am, so quick replies would be appreciated.

DS is 4YO, 44 lbs, and something like 44" (wears size 5). He normally rides in a frontier, but I have a bubblebum for my nephew.

DH scheduled a car appt tomorrow morning (which we desperately need to get done), and I scheduled a work-related meeting a few miles from the shop thinking we could all go over together (with both cars), drop off car 1, and he could drop me off at my meeting and do something with DS while we waited. But DH got scheduled to work (and 'forgot' he had a conflict).

So now I am stuck with my 4YO and a car appt ~3 miles from my meeting. Car appt is at 11 and meeting is at 1. So I'm thinking my choices are:
1) Cancel car appt or meeting. Car is overdue, and meeting is a practice for a friend's phd defense so cannot be rescheduled (no time before the defense).
2) Take DS and try to bus to meeting from shop. Main problem with this is it involves a ~1 mile walk on a rather busy street (not sure if there is a sidewalk on much of it).
3) Take DS and use the shuttle service (in a minivan) with the bubblebum. I suppose I could sit next to him. He meets the minimums and isn't particularly squirmy for a 4YO, but isn't booster trained at all.

Then of course I have to keep him occupied at the meeting and/or shop, which is it's own challenge, but I can probably handle that.

WWYD?

For a short trip and if you're able to sit near him to make sure he stays in place I would use the bubble bum for a 4yo. The minivan will have head support for him, right?

It seems to me that #2, if no sidewalks, likely meets or exceeds the danger of #3.

I would probably be okay opting for #3. Any potential the shop would drop you off in your own vehicle? That would require more entertainment time at the destination, but less uncertainty in travel. If not, I would go with the Bubblebum, after talking to kiddo about it. Just make sure you both have lap-shoulder belts and head support, which might equal sitting on opposite sides of the bench.

We ended up using the bubblebum, and really it fit him very well, and he was still for the few mile drive. I think it was the right decision. He said he liked his frontier more, though (which is great since I won't have any fights with him to keep him in the harness).