What if you can’t borrow a pwc of the same model? If one were to get a used van that already had the modifications for a pwc, what are the odds that the pwc wouldn’t fit?.
Karen, I encourage getting a wheelchair early. Advantages include:
1. You can more easily adjust the wheelchair to fit you perfectly. While my first wheelchair was amazingly comfortable when I got it, I spent quite a few hours fine tuning the fit to be perfect. Had I waited until I lost mobility I would have needed to rely on others to make those adjustments as I sat in the wheelchair. That is not very practical.
2. A new wheelchair may have some issues and may need to spend some time in the shop. Getting past this period while you still have some mobility is much easier than when you are dependent on a wheelchair.
3. Getting a wheelchair early allows you to leisurely shop for a wheelchair van that will fit your wheelchair.
So, in answer to your first question, I recommend getting the wheelchair before you need to get the van. That way, you will have your wheelchair to test fit in the van.
If you don't get the wheelchair before the van, you may be able to borrow or rent one. I know that my local NuMotion would allow me to borrow one of their demo wheelchairs. I would have the van seller meet me at NuMotion and test the fit with one or more of NuMotion's wheelchairs.
As for your second question, it all depends.
If you are talking about a minivan, it is quite likely that a given wheelchair will not fit into a given minivan. I have not tried to put my wheelchair into a minivan, but based on my research their is only one conversion that could potentially fit my main wheelchair and me. For a smaller person with a smaller wheelchair, there are certainly more options.
For a full-sized van (such as a chevrolet express conversion van with a raised roof), it is very likely that most group 3 and 4 wheelchairs will fit (my C500s vS is a group 4 wheelchair, apparently).
For Sprinter, Transit, and ProMaster vans, it is likely that most wheelchairs and their occupants will fit.
For ATC Silverado/Sierra conversions (pickup trucks), it is a very tight fit. I have not yet figured how to do this. They have a template online that you can use but I have heard of stories where that did not work out so well (wheelchair did not fit when the template said it would). About the only sure way I know of is to drive to Fort Wayne, IN and test my wheelchair in one of their pickups (or find one locally).
Here are two other points to consider:
1. Not all vans have doors tall enough to accommodate the wheelchair and rider. Mine does not. I have to recline the wheelchair to load and unload. I have a memory setting configured in the wheelchair so that I don't have to guess about how far to recline the wheelchair. It is doable, but is a hassle. I look forward to having a wheelchair vehicle someday where this is not necessary.
2. Securing the wheelchair and the rider is important. I can still transfer into a normal seat, so only need to secure the wheelchair. Three options I know of are EZ Lock, QLock, and tiedowns. I would not want tiedowns at all. I have an EZ Lock and it has been fine. I presume a QLock would also be fine, but I don't have any experience them.
If you are going to ride in the wheelchair you will need to have an appropriate seat belt setup. A mobility shop should be able to configure this for you. My van came with a removable seat belt for the wheelchair occupant.
Steve