Hello Michael,
I am sorry to read of your loss, I sincerely hope that you can come to terms with you new situation and still have happy memories of the time you spent together.
May I just offer some advice about choosing which mover to go for. You have a very specific need for the mover to safely handle your caravan on a 1 in 4 slope. This must include starting and even more importantly Stopping on the slope. Make it very clear to your supplier that this criteria is critical, and forms the basis of your order.
My reason for advising this, is because the seller is obliged to sell goods that are fit for purpose. If the seller is clearly made aware of the use and duty it will be put to, they then have the choice to supply if they are confident of its capability, or decline if they feel that can't guarantee it will work under the conditions you have specified. This protects both you and the seller.
Heaven forbid that it will fail, but if it does, then the seller cannot claim they did not know the use to which it was to be put, and that will strengthen any claim you have to get it repaired or replaced.
I believe that most manufacturers claim their product will over come a 1 in 4 obstetrical, but you must find out about use on a continuous 1 in 4 slope.