Would you change only the front shocks?

Smitty77 is right on with advise. All it takes is money. You can spend all you want too to solve a bounce. Each $1,000 you throw at it will make it a little bit better. After 6 or 8 thousand, you have probably done all you can do. then trade it and start all over again.

You only asked about front shocks. And yes, I would have no problem changing them out by themselves first. If your Spartan is non IFS (not up on 2002 year Newmar Spartans), I would go with the Koni FSD's. If IFS, and at 40' (not sure of your length), I would go with Koni Adjustable, and probably start on setting 2 position. (If you go the Koni Adjustable route, make sure they are SP3 generation, as some vendors still have New Old Stock SP2 generation.) (Other Newmar owners of that era, can tell you the front is IFS, if the FSD's are robust enough to handle the front end. On our 2004 era Country Coach IFS, they were not able to keep up with the job, and until the SP3 generation adjustable came out, even the older SP1 (came stock) and SP2 had trouble containing the front end.

In addition to shocks, on a 2002 with 85K chassis, I would have a full suspension inspection completed, and replace bushings and rubber related wear items at the same time. Yep, full wheel alignment included too.

(As info, due to some negotiating at time of used purchase, we had credits applied towards shocks. So I used this to subsidize the purchase of Road Kings. Without the credit, I would have probably just added Road Kings to the front, and then Koni SP3 to the Drive and Tag. I also added the Super Steer Motion Control Units (MCU's) front and rear. Our coach handled at a 6 out of 10 level when we purchased it. These incremental changes moved this up to a solid 8.5 out of 10 for handling. Not for canyon racing, but for emergency handling if needed.)

Best of luck, have fun, be safe,
Smitty

Henderson Lineup is where I got my FSD's

Change the fronts only. After that, drive the coach to see if you need to change the rear shocks also.

If you are planning (or might like to!) to travel to southern Oregon, try these guys. Henderson Lineup in Grants Pass.

You can have a tech take it and you on a test drive to discuss the problem, then they give you a list of suggested improvements they can make, in order of most effective. With us they suggested we do a couple of things then if we thought we needed more to drop by on our way back in the spring. Haven't needed the other expensive options.

Our previous coach a 31' Gulfstream Sun Voyager DP porpoised something awful when we bought it used with 28,000 miles on it. It had Bilsteins. I replaced the front only with Koni FSD shocks and the porpoising was GONE!

I owned a 2005 HR Ambassador. It had 4 shocks on the front. 2 in front of the front axle and 2 behind. I pulled all the shocks, put the 2 best original shocks back on in front of the axle and 2 new Blistiens behind the axle. Sure did help the ride and wind effect from big trucks. Change the 2 front ones and if you are not satisfied, then change the rear ones.

If you have a tag axle the tag and drive axle shocks can add extra bounce to the front end.
85K I would do them all.

I would have no problem with replacing the front only. In fact I'm going to do just that this year but with Koni. Then the next year I'll do the rears. With so many shocks (8 I believe) it simply a matter of spreading the expense.

You can just replace the fronts, but with 85K on them I would do them all.